JavaScript Casino games, slot game js.

Slot game js

The most important thing to note about this form of casino game is the fact that it is live and requires multiple players. For the game to work the javascript code needs to be able to connect the individual players together. Each player will only be able to see their own card hands. All other card hands need to be kept secret from the other players. If this can not be done properly then the game is not only ineffective but potentially fraudulent. In order to effectively understand the vast applications javascript has in the development of casino games it is useful to analyse an example. In this article we will be looking at online poker games.

Javascript casino games

In order to best understand how javascript is used it is useful to analyse an example of a casino game. In this article we will be looking at slot machines.

A traditional slot machine contains multiple columns of numbers or images. The columns spin and displace the images or numbers along with it. Wins are determined depending on how many are matching when the spin has ended.

Javascript can be employed to create a fun, aesthetically pleasing and enticing slot machine game. A designer could pick a theme and base the game around this. For our example we will choose space as the core theme and visual motif.

Background

First the casino game designer will need to decide on the background image. They could choose space. This image does not have to remain static. With javascript coding the background could be an animation of an epic space battle that changes depending on if the player wins or loses.

Next they will have to design the slots themselves. Each slot element could be an animated image. For instance the slots could be gifs of aliens, planets or astronauts. Interactive codes could be written into the slot images using javascript. If a player wins a or loses the image animation could display a different graphic. For instance if the player wins the alien could smile or if they lose a planet could explode.

The most important reason for using javascript as a programme for developing an online casino game is the fact it has so many interactive applications. It is crucial that the game player can interact with the onscreen site. The scripting language allows the player to click a button to spin the machine.

Underneath or above the interactive game display a graphical column containing the player’s progress information can be displayed. This can include a countdown timer, player score, winnings total and rank scoreboard. Javascript code is utilised not only for the figures within these columns to change via animation. They also control the inner working that calculate the figures themselves.

But what about getting the player to click on the game page in the first place? How do you advertise the game effectively on a casino home page?

Animations

This can be done by utilising javascript as a coding language. Graphic web designers can creating an eye popping graphical animation that also doubles as a hyperlink to the game itself. This graphical advertisement is usually colorful and fits in with the visual theme of the game.

When the prospective casino game player clicks on this advertisement image the javascript code will send them to the game page. Often in order to create an effective advertisement the programmer should not just have experience in javascript. They should also be qualified in graphic design. This too goes for designing the visual theme and aesthetic of the game itself. If a programmer feels they do not have the design skills for this it is advisable to hire a third party to outsource the artwork.

Design matters

In order to effectively understand the vast applications javascript has in the development of casino games it is useful to analyse an example. In this article we will be looking at online poker games.

The most important thing to note about this form of casino game is the fact that it is live and requires multiple players. For the game to work the javascript code needs to be able to connect the individual players together. Each player will only be able to see their own card hands. All other card hands need to be kept secret from the other players. If this can not be done properly then the game is not only ineffective but potentially fraudulent.

Thankfully, javascript is the ideal language to be utilised for the task. It is quick, easy to use and has a vast amount of application potential. In terms of graphical information code the first thing to note is that an online poker game will typically have a card table in the centre of the screen. The individual player will have their score, cards and avatar in the middle foreground of the table.

Javascript can allow their score to automatically update and have their avatar be an animated gif. In terms of interactive elements the script allows players the options of whether to fold, call or raise their chips. Poker is a complex game so for it to work a complex game code needs to be embedded into the javascript file. The chips the player has are not just animated elements. They must also be correct representations of their winnings. When they place their graphical chip elements onto the table a separate algorithm must be working behind the scenes which keeps up how much total money has been lost or won by the player.

Javascript is the ideal language to implement this. It is used only practically every web browser, wherever there are interactive elements. Game designer can use it to invent creative, innovative work for casino sites. When designing a poker game in particular, javascript has many other potential for interactive elements. If the player wants to message their rivals then a chat box can be placed on the corner of the game screen. They can also have a settings bar where players can preset game decisions such as when to auto-fold or sit out the next hand.

In order to design an online casino poker game the designer will need extensive experience in programming. While it is true that you don’t need expertise in software design to get to grips with javascript it is important to recognise how complex this form of casino game is. You will need coding that will be able to not only accurately calculate game score, winnings and bets. The coding will also need to display this information via the animation graphics and vice versa. Javascript is an essential language for developing an online casino game. All programmers use it when creating interactive web pages, as this example shows.

Slot game js

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New casino sites to play real money

This is an example slot game written in javascript. This is a fullstack javascript application (hackathon starter) short info about technology stack

• Client side - ES6 with browserify and babelify, sass (node-sass)


• Server side - nodejs with express, pug for view render


• Tests - mocha and supertest

After this command check http://localhost:8080/ from your browser.

Only backend outcome api tests are written. You can running it with:

Slot machine in javascript

Recently somebody talked to me about creating a slot machine. I looked on the web and could not find any good slot machine implementation in javascript. So I decided to write a quick one. My implementation uses jquery and a couple of jquery plugins for animation. Spritely is a wonderful jquery plugin for background animation. I also used a plugin for animating background-position since jquery does not support it natively.

Lets start building the slot machine. Demo here

First of all we need a sprite for our slot machine. This sprite is basically a reel which in motion simulates a slot. Its preferable to have blurred copy of this reel too, to show the effect of motion. For the purpose of this demo I got the sprite from internet.

The markup is very straightforward. We just need placeholders for 3 slots and a button as controller.

Lets got through the javascript now. First we need a class for a slot. Our 3 slots will be objects of this class.

Why do we need so many paramaters for a slot machine? That’s because each slot of an ideal slot machine should have different acceleration and speed. Also its good to have different max speeds.
Our slot class will have 4 member functions:

• Start() – starts a slot


• Stop() – stops a slot


• Finalpos() – finds the final position of the slot when its stopped


• Reset() – resets a slot for another run

How it works?

Initially we create an object for each slot of the slot machine. We pass different values for the max-speed and speed-stepper to the constructor.

Var a = new slot('#slot1', 30, 1), b = new slot('#slot2', 45, 2), c = new slot('#slot3', 70, 3);

When a user presses ‘start’, start method is called for each slot. This method kicks off the slot and increments the speed at regular intervals. This can be done using setinterval. Code below:

73 comments on "slot machine in javascript"

Hello……I am currently trying to teach myself javascript…or some sort of programming……..I thought this was really cool what you made…..U have any tips of where or how to start….I bought some books so i am currently reading those….And trying to write scripts as i go along
by the way how long did it take you to write out all the scripting for this page?

Get your javascript concepts right. Follow blogs of javascript experts. Pick up some small problem and think how you can solve it in javascript. The best guide I have found is https://developer.Mozilla.Org/en/javascript/guide

Nice work there, actually I’m planning to use your javascript slot machine but with a bit modification, is it possible to predetermine the winner? I mean I can set when will be the winning combination will occur.

Like people will have 3 tries to play this but my app will be the one to decide when the winning combination will occur?

Please provide me an info how to do so and which part of the code need to make some changes as I don’t want to mess up the totality of your work.

Did you have found a solution to know the result of the position of each slot beacause i have the same question than herz.

You can predetermine the results initially and finish the slots at desired position to simulate winning.

I found out an error on firefox there, after start for awhile all 3 slot turn into blanks slot.

Does it ever win though? I played it about 100 times and couldn’t win… ��

Its really cool though – just wish I had a more relevant site to add it to. To the commetor who queried if it worked in firefox – it worked fine for me every time.

I never wrote it as an actual game. My intention was to show a way to implement the slot machine in javascript. So all the combinations of the slots are evenly distributed. You can add some tweaks to increase the chances of winning.

Are you (saurabh odhyan) available for hire for a simple project?

If yes email me and I will tell you about it, it should be simpler than your slot machine.

Hi saurabh,
awesome script – I would be happy to use it in a small gig I am putting up for a team game for my colleagues – is there a chance you are willing to help me here and provide me with 3 winning scenarios (and one loosing �� ) for some $$$? I wish i had the brains to do it myself but I am sure you are the best man for the job plus I am always happy to donate for open source work ��

Hi saurabh, can you please provide a little more details as to how you can increase the odds of winning? Thanks for this tutorial.

Decrease the number of images used. I’ve tried seven various images (apples, etc), 1 wild and 1 scatter, for a total of nine, and it keeps the player playing without ‘running out of money’. (unless they are truly ‘unlucky’ ��

Hi jerry,
I tried reducing the number of images, but am not having any luck in increasing the chances of winning.,

Also, when the images reach their final position, I take a look at the elements, and I see things like this:

My question is – how does the number 10996 relate to the image? My image that shows up with that background position is in the array at 0, 237, 454, 696, 913, and 1157 (as you can see, putting one image in so many spots was my attempt to increase chances of winning, but it seems to make no difference). Any advice from you or saurabh would be greatly appreciated.

Try (google) “stacked images”. That is, load 3 or 4 of each image into each slot. Then, randomize a key and sort. At times, one image will be repeated within a/any slot, sometimes 4 in a row. Just remember, if they win, multiple lines will have to be computed.

This whole casino is javascript I think
http://www.Social-casino.Co.Uk

Hi! This is a nice tutorial!
However I can’t find how to modify the results. Could you please enlighten me on that?
Thank you.

Im using your slots program in my facebook app. Kudos!

How effective is javascript if we want to develop a facebook social game like farmville,slotomania etc

We have started a new start up clipinmedia focused on developing facebook social games for clients.Our next project is to develop a social game like https://apps.Facebook.Com/slotomania/ ( it’s developed in flash + PHP ) max numbers of games on facebook are made using flash.But as browser games can also be developed using javascript as this slot’s game https://apps.Facebook.Com/nonstop_casino (is developed using javascript + PHP)

Second game (javascript+php game) is less attractive as far as graphics are concenred but it’s providing almost same gameplay experience as of other flash games.

Would you like to share your opinion in case we don’t need highly attractive gameplay will this ( javascript + PHP ) model will work what problems can come into play at later stages.Or javacript will be perfectly fine to work with.

Has anyone tried making 5 reels instead of 3?

Hi,this is a nice tutorial!

But when you leave machine to roll after some time you will find all slot image is disappear.

Can u tell your logic here…?

Slot.Prototype.Finalpos = function() <
var el = this.El,
pos,
posmin = 2000000000,
best,
bgpos,
i,
j,
k;

El_id = $(el).Attr(‘id’);
pos = document.Getelementbyid(el_id).Style.Backgroundposition;
pos = pos.Split(‘ ‘)[1];
pos = parseint(pos, 10);

Nice looking slot machine motion.
Unfortunately, when I try to use your HTML and scripts on my local machine to play around with the code, it does not work: it’s only showing three white squares, no background image at all …

How can I solve this and get this nice thing running? ��

I am trying to replace some of the images in the strips of images (normal/blurred) and was wondering if you’d tell me what program/filter you used to get the blurred effect?

I used the filter “motion blur” in photoshop, worked perfect. Other software like gimp or photoimpact have this filter, too. ��

Javascript/CSS based 5 reel slot. My approach was to use the DIV element for the reels. For each spin, randomize x number of images and replace the contents of each reel with the image objects (contained within their own div). Spinning animation was accomplished using a timer (setinterval), and the reels “spun” by inserting the lastchild before the firstchild, and then removing the lastchild. Each reel has a different timer event with a different millisecond setting, and each reel is clearinterval(ed) after each slot replacement. The reels are stopped sequencially left to right by maintaining a “loop count”.

Works the same in all browsers. I’ll have it up and public soon. I hope this approach stirs some of the fog regarding animation and javascript.

Anyone figure out how to determine when it wins? Like for example win on 3rd pull? Please tell how it’s modified to do that.

Also, how can i make a wild card, or make it so 2 of a kind wins?
I tried editing the codes and adding more entries to that win array, but the slot machine stopped working.

When i say wild card, i mean anytime 1 of a certain one appears in any column, then it’s a win. For example, let’s say the number 7 is a wildcard. If a 7 appears once, twice, or three times, then it’s a win.

@leo. Therein lies the problem, and it is solved through logic implemented in javascript. You must examine each slot within each reel, one “winning combination” at a time. “lots of code” but very doable. I’m working on one now in order to complete my slot machine, and will post my findings here.
I’m also trying to implement this blogs solution to achieve a better ‘spinning effect’.
Lots of good discusstion here. Please keep it going. Animation in javascript is the only way we will all move away from flash.

So far …
I grab the image.Src to compare those images in the 5reels*3slots view. (note: my machine has only 9 winning lines, but has wild cards and ‘scatter’ wins. 1 wild and 1 scatter per reel. (the difference is wild is wild for all images except scatter. Scatter is a win regardless of line or reel.)
starting with reel 9 combination, I compare the src of reel1 to reel2, and if there is a match (or a wild), I continue to reel3. If a match is found on reel3, we have a winning line, and I display the line9 graphic, and continue to line4 and line5 to determine the amount won. I then do the same for line 8, through line 1. After that I search for “scatters”. Once the sum of ‘winnings’ is determined, I display the amount and roll it into the players holdings.

Hi, has anyone fixed the problem for firefox ?! The background iamge simply disapeare at certain point. The problem seems to be in the spritely plugin here … help please

Hi is it possible to stop the slot automatically? Thanks! ��

*excellent* tutorial – this is exactly what I needed for a cute project I was working on for my blog (see the result here: http://unsolicited.Elementfx.Com/OSM/OSM.Html – and, you’re credited ��

Unfortunately, I have the same problem as chaara and loki – after one spin, the 1st symbol turns “white” and does not display on subsequent spins. While I have some programming experience (sadly, from 1974!), I’m not javascript savvy: is there a solution to this?

I think I found the problem: if I start the game before the page loads completely (ie: before every element loads, including ads & trackers) I have the problem. If I wait for the page to completely load, no problem ��

Interesting approach. Actual slot machines use virtual reels, and the physical reels you see are just an animation for the shill to look at that displays the final, predetermined result (the virtual reels take the result based on an extremely large random number, and do not necessarily have the same amount of each symbols virtual representation as shown on the physical wheel). You could take an extremely large number, run it against a set of extremely large tables (the virtual reels), then animate it to show the calculated result. More code, but smaller images.

Just a completely different answer here:

Do u need a licence to run this script as a gambling machine ? Imagine that I am not charging user to play it or to join the site, but they can get points if they win, and with those points they can buy images as prizes, or similar .. Even more they can upgrade their account if they have x points ?! Otherwise, upgrading costs money ..

I am just trying to guess the scenario where it could be ilegal!

For those puzzled about what is going on in finalpos… I think the nested loops [for(i=0 …] can be replaced with this code (maybe a bit more comprehensive):

Var relativepos = pos % imgheight;
var imgbasepos = pos – relativepos;
for(i=posarr.Length-1;i>=0;i–) <
if(posarr[i]
pete
may 3, 2013 1:40 pm

Just found out that posarr is not correctly commented with the symbols. It makes no difference for this example (since the actual symbol does not matter here), but may be confusing when working with the code.

Changed posarr declaration to:
posarr = [ // positions on reel image, pixel offset from bottom(!)
80, // 0 cherry
165, // 1 banana
237, // 2 guava
310, // 3 bar
378, // 4 number7
454, // 5 orange
539, // 6 cherry
624, // 7 banana
696, // 8 guava
769, // 9 bar
837, // 10 number7
913, // 11 orange
1000, // 12 cherry
1085, // 13 banana
1157, // 14 guava
1230, // 15 bar
1298, // 16 number 7
1374 // 17 orange
];

Btw: I think the guava is rather a pear ��

Hello,
how to set this to work with new version of jquery like 1.8.2 ?

How to set all image on same align ? When they stop ?

Firstly thank you for this excellent slots script!

I am trying to customise it so that this.Pos is set to a specific pixel location as not all of my icons are the same (for example s1:’W’, s2:’I’, s3:’N’)

Your script uses a function to locate the best final position based on how close the icon is.

This is my modified function:

Wanna checkout a fully functional js slot machine with sound, checkout grabgreen.Luckydiem.Com

This is great, your example works beautifully and your explanation is clear. Glad you hosted it at github too. Very helpful.

Saurabh, thank you SO much for this. It’s really cool. I really like how flexible the slot machine and imagery are.

If you don’t want an immediate focused to blurred image, add this to your stylesheet for the .Slot div:

-webkit-transition: background-image 1.7s ease-in-out;
-moz-transition: background-image 1.7s ease-in-out;
-ms-transition: background-image 1.7s ease-in-out;
-o-transition: background-image 1.7s ease-in-out;
transition: background-image 1.7s ease-in-out;

Currently, the backround-image doesn’t work on firefox. Progressive enhancement ��

Hello,
how do I make the script to always gave the same results, or that I could ask what the script outputs the result?

I read your post and wished I’d written it

Is there any way to arrange the result to be always winning.

Nice one! This post is 6 years old and it still rocks!

Hi mr odhyan, awesome apps you have here.. Btw, can i used this code for my campaigns? Do you need credit for this? Please let me know…

Awesome. I came across this on google as I want to make a slotmachine implementation myself. I tried a few times and I was actually a winner. Great post!

Нello there, you have done an incredible jоb.
I’ll definitely digg it annd persоnally recommend to my friends.
I’m cojfident they’ll be benefited from this site.

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Hi.. Can u teach me.. Gaming slot 918kiss.Com. Im sory but my englih spoken very poor..

Hi.. Can u teach me.. Gaming slot 918kiss.Com. Im sory but my englih spoken very poor..

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Javascript slot machine

Code for your new or existing gambling site

While talking about casinos and gambling, the first thought that comes into our mind is about a slot machine. After the advancement in technological, it is easy to start or integrate slot games online.

AIS technolabs has technical experts that help in building these modern-day slot machines for online gambling. Our team of coders has keen knowledge about coding and programming required for the business of casinos and gambling.

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Attain the wonderful benefits by

Our javascript slot machine code for

Your online gambling site and app

At AIS technolabs, we offer a fully customizable javascript slot machine code as per the demand of our clients. Our esteemed developers provide various instructions needed for gaming system in different programming languages such as C, C++ as well as java. Moreover, we help our clients to build their javascript slot machine and that too at very affordable rates.

We are one of the leading javascript slot machine code providers that offer quality products and excellent game varieties for the gaming industry. Our skilled and professional developers are very innovative and creative those who have a complete understanding of online gaming and casino software. Furthermore, the client can hire and choose the best slot machine code developer from us for their gambling sites that develop custom slot machine codes according to their requirements. Our developed code will help our clients with all the essential information for playing safely and full of fun.

Below the several advantages of our javascript slot machine code

Slot machine

Slot machine with fruit theme

The game starts with 5000 credits, and you can bet 30, 60 or 90 credits. Click on the bet buttons to make a bet, and then press the "spin" button. The game calculates the winnings based on the bet level, the configuration of the matching pattern, and the value of the matching symbol. If you lose all the credits and go bankrupt, you have to refresh the page to re-start the game.

Slot machines were invented at the end of the 19th century. They became popular in las vegas and in many locations where gambling was allowed. Mechanical machines eventually were superseded by electronic machines that require less maintenance and can be better controlled by the casinos to prevent cheating and to guarantee more consistent profits. Modern slots are programmed with a variety of themes such as storybook fables and even chinese lucky charm symbols to enhance their general appeal. In the era of the internet it is now even possible to play bitcoin casino slots, but there are a number of differences between the online and physical reel versions.

Slot machines are called "fruit machines" in britain and "poker machines" in australia. The casino gambling machines usually have three or more reels that spin when a button is pushed. Slot machines are also called one-armed bandits because slot machines were originally operated by a lever (arm) on the side of the machine, and because they can leave a gambler penniless.

Some slot machines simulate card games and others have special themes. The most popular slot machines in las vegas and atlantic city casinos are wheel of fortune, fort knox, mr. Cashman, little lucy, white ice, haywire, ten times, jackpot party, wild eights, triple cash, wild cherry, double diamond haywire, triple black tie, lucky four leaf clover, pinball, white ice, galileoвђ™s gold, blazing sevens, double diamond, double double diamond, triple diamond, ten times, tabasco, bonus poker, double lucky 7's, sizzling 7's, and blazing 7's.

Simple slot machine game using HTML5 part 1: basics

Here is overview on how to make simple slot machine with HTML5. This demonstrates the basic structure of HTML5 game and how to use dynamically created graphics.

Slot machine has typically reels with images and player just initiates the action and waits until reels stop. 1 or more in single line usually determine the winning condition. In this game player wins if he or she gets more than one gold bar in row.

How it works

Slot machine is a single HTML page that includes the game code, webfont and jquery. When loaded it runs slotgame() function that initializes and runs the game.

HTML page has 3 narrow and tall HTML5 canvases, these are the reels. They are located inside div container “reels” that shows only a limited window at any time, hiding the rest of the canvases.

On initialization, game preloads the 6 image assets. Preloading is simply done by creating image object for each asset and listening its load event. Preloading is required, because otherwise game could not draw the reel canvases on initialization.

Game draws the pictures in random order on each canvas reel with shadow and slot separator bars.

The reels are not redrawn after this, but when moving they are simply translated with CSS3 transform downwards and when they reach threshold they are moved back to beginning. Threshold and reset offset is selected so that after the reset images are shown on same locations. This creates illusion of constantly rotating wheel. This is why images on borders are twice in the reel, so we avoid showing canvas bottom or top in any situation.
Click ‘toggle reels’ button on top left corner of the game page to toggle the reel visibility while it’s spinning, seeing reels in action makes explanation above much easier to understand

Here is image where reel container overflow is set to visible.

Game loop is simple, it starts when player clicks ‘play’ and runs on every animation frame updating the reel locations based on game state and “draws” them on screen, or actually as explained earlier just translates their locations. Result is predetermined on each roll start and when each reel stop, its locked on the correct image. Update loop tries to make this when correct image is close to this location, so the jump is not too abrupt (see function _check_slot in slot.Js for details).

Each browser has still different name for the transform so initialization code determines the correct CSS name and if browser has hardware accelerated 3d version.

Slot machine the fruits - HTML5 casino game

Slot machine – the fruits is a HTML5 casino game. Enjoy this coloured slot machine with classic fruit symbols!

This game has been developed in HTML5/js and third-party library createjs – http://createjs.Com/ (not construct2 or other framework).

The ZIP package contains the game with 1500×640 resolution that scales to fit the current screen device.
The game is fully compatible with all most common mobile devices.
WARNING:
sounds are enabled for mobile but we can’t grant full audio compatibility on all mobile devices due to some well-know issue between some mobile-browser and HTML5.
So if you want to avoid sound loading, please read the documentation
sounds can’t be enabled for windows phone as this kind of device have unsolvable issues with and tag.

This game is fully compatible with CTL arcade

A wordpress plugin that allows you to create a real arcade on your website.

Easy to install

With CTL arcade you can:

• Monetize with your games adding ads banners


• Promote your website with social share buttons


• Improve our games with leaderboard, and rating feature
  

=== even if we do our best to minimise any inconvenience, we can’t ensure the full compatibility of all our games on every device and every operating system update.
Thank you for the understanding. ===

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State of the art

Developing an HTML mobile slot machine game from scratch

By mihhail lapushkin

For the past 9 months at ignite we’ve been developing an HTML slot machine game for ios devices. Seems like no big deal, but the thing is that our customer did not want to make yet another game with crappy graphics and simple animations. Instead, our goal was to provide retina quality graphics with stylish, performant animations and beautiful sound tracks. Speaking of sound quality, our composer was the same guy that produced music for angry birds. Pretty cool, huh? ��

So, without further ado I present to you:

[ casino island deluxe the mobile sequel of casino island ]

In this blog post I am going to go through the core technical decisions that we had to make, challenges that we had to deal with and solutions that we have worked out to make this game kick some serious ass.

Development setup

To start off, I’ll cover the way we’ve organized our development process. The goal was simple – we needed something, which would allow us to constantly check our stuff out on real devices. Syncing seemed like the best way to go, so we’ve setup a sync system (winscp on windows, rsync on unix) between our local workspace and the development environment. Once you hit save, changes are synced to the server and you can immediately check them out in the mobile browser. Each developer has his own development URL and the committed code deploys to the stable version URL. Easy!

Game structure

DOM vs canvas

We’ve decided to go with DOM, not canvas. In my very first blog post I’ve explained some key differences between those approaches. Being already more experienced by now, I can say that the core benefits of DOM are:

• Easy to use and prototype CSS animations


• Declarative structure through HTML


• Testability

• Has a tendency to gain speed with time


• Can support more animations without performance issues


• Is consistent across browsers


• Provides more options to play with masks and filters

At the time when we started working on our game CSS animations outperformed canvas by quite a lot, so that’s why we went with DOM. However, if you’re thinking about the future then canvas might be the way to go. Consistency across browsers is a major bonus especially for big companies, since it means lower maintenance costs and greater portability – pretty much the same arguments that led flash to become so popular in the browser world. Of course, canvas heavily lacks in tooling support, but it’s something we have to live with right now.

Layout

Our positioning system mostly resembles the already mentioned flash. Every element in our game has an absolute position and is moved to its place using pixel offsets on top and left. Parents place their children, children place their children and so on.

The cool thing that we have discovered is that retina screens don’t require any additional handling at all. If the images are double in size, they will just look better on retina screen without the need to change any stylesheets, whose measurements are designed for regular screens i.E. CSS does not care about your devicepixelratio. Pretty neat!

Conventions – a solid foundation

Having already worked in a hand full of projects before I joined this one, I’ve noticed a certain pattern of problems that usually arise in front-end development. Those problems typically fall in one of three categories:

• Ad-hoc javascript


• Ad-hoc CSS rules


• Ad-hoc HTML structure

Under ad-hocness I mean that stuff is written:

• As separate pieces that are glued together to existing codebase


• Without any thought of the bigger picture


• Often without proper knowledge of front-end technologies and patterns

I should know, my code used to be quite messy as well. However, continuing like that in a project, which is 90% front-end would have been a suicide, thus it was decided that we should work out some set of rules for ourselves. Next I will explain what we ended up with after some period of trial and error.

We try to push as much as possible to static HTML, meaning that we hardly create any HTML in the javascript, even if it means duplicating the same HTML code multiple times. This allows us to have a fantastic overview of the whole game structure and, basically, to use HTML as a structural template. Javascript thus stays clean, concentrating on its main role – dispatching events and switching stuff on and off.

Javascript

External

For DOM manipulation and AJAX we are using jquery in this project, but in the future we will probably switch to a simple, lightweight in-house library, since for a game, which needs to support only webkit browsers jquery is a definite overkill. For sounds and preloading we use soundjs and preloadjs. That’s pretty much all of our dependencies.

Internal

For the application code we decided to go with pure OOP as much as it is possible in javascript. Every class has a separate .Js file with its name and for view classes we also add a companion .Css file with the same name. Thus we make everything a component that can be easily modified and reused.

Here is sort of a JS class template that we have worked out for ourselves:

CSS is not a programming language in a traditional sense, thus for a typical developer it is quite hard to reason about it. Yet CSS is very important, as it builds the face of your application and usually needs to change more often than the logic. Therefore, understanding how to build scalability into CSS from the ground up is vital for success of any project.

Most of the stuff on this topic is covered in one of my blog posts. At first, we took almost everything in and then step by step started evaluating if a certain rule actually brings us any value or just adds unnecessary complexity. Our modifications and additions are listed next.

No preprocessors

There’s nothing bad about them though. We’ve just decided to keep things as bare bone as possible.

CSS animations are part of state group

Basically, it is the same change of state, but just prolonged in time. For the sake of clarity, we usually name them after continuous actions (is-rising, is-moving), unlike regular state classes, which are named after completed actions (is-hidden, is-selected).

Limit the usage of layout classes

At some point of time we understood that having layout classes everywhere just polluted our code. Unlike a website, the game does not have a lot of reusable elements, thus it is useless to separate layout from styling of every single visual element that would appear only once. We decided to limit layout class usage only to cases, where they actually make sense and merge them with styling code for remaining rules.

Separate logic classes from styling classes

After some time we also understood that it is a good thing to separate javascript hooks (classes that you reference in the code) from styling classes. This involves having to attach more classes to your elements, but completely separates your JS code from CSS. You can rename and remove styling classes without any harm to your logic and you can rename and move the hooks around the DOM without any impact to the visual look. Perfect!

Javascript hook classes have their own js- prefix and since those classes are component-scoped they don’t require namespacing or any other naming conventions.

To give an example of how this works. Imagine a label, which we would style through mycomponent__my-label class and insert a dynamic label through js-label class:

Now at some point we decide that we need a span to center the text vertically and thanks to our fancy design decision we can do it without any changes to the javascript code.

Architecture

Continuing the talk about code structure, we now move on to the actual architecture of our game. I would say that no surprises await us here. We are using the good old MVC approach coupled with a thin network layer (which would probably get merged with the model at some point).

Network

• Makes AJAX requests


• Receives and parses responses


• Fires events once response is received


• Updates model with response data

Model

• Wraps DOM operations


• Listens for UI events


• Performs animations


• Switches stuff on and off


• Updates itself based on model state

Controller

• Handles view and network events


• Calls view and network methods


• Synchronizes animations

The game itself is partitioned into several independent clients. Each client is responsible for a certain device type (iphone, ipad, android phone etc). Special device detection component is used to redirect the player to the correct client folder.

Animations

Animations are undeniably the heart of your game. Knowing what the browser offers you in this field and how to use it efficiently is the key to success for every web game developer.

Forget about JS animations

One mistake that we’ve made in the very beginning and the one that you should not repeat is thinking that JS animations are good enough. Well, they are not! Believe me.

Transitions vs animations

First thing that you should know about animating with CSS is that you have two big guns in your arsenal.

Transitions

Transitions animate changes in CSS properties. You specify what properties are animated, for how long and with what easing. When this property is updated it will smoothly transition between the current and the new value. This works both for single value properties like opacity and multi value like color.

Transitions are not very suitable for complex animations. Their main use case is when you want to animate something dynamic, which cannot be easily predefined with key frames.

In our game we use transitions only in two places: preloader progress bar smoothing and animating boat movement to different islands in the bonus game.

Animations

CSS animations provide a versatile API for complex, multi step, key frame based animations. You describe the movement with a special @keyframes rule and then reference this declaration along with duration, easing and a whole bunch of other properties. Usually, animations are applied thorough some on/off state classes.

The key to writing good animations is knowing and using every configuration property available. Take your time to study them all. For example, for me it was a surprise that animations can actually retain its final position through fill-mode. For quite a while a thought it was only possible through transitions. Other interesting thing is timing-function: steps(n) – veery useful in sprite animations.

GPU acceleration is king

Now I’ve told you that you should drop the idea of using JS animations in favor of CSS ones. Actually, I was not specific enough – GPU accelerated CSS ones. If you want to have multiple animations running at the same time you’re going to need to use the graphics card, otherwise your game would just die. This means one thing and one thing only – translate3d. Stick it wherever possible.

For example, our initial version of the bonus game used only a few hardware accelerated animations. And boy did it lag! After some iterations we were able to push everything to GPU including sprite animations. Immediately, all of our performance problems got solved.

Don’t forget about 3D quirks

While 3d transforms are awesome, they may have some interesting side effects that you should be aware of. Even though your z-coordinate will always be 0, you are still operating in the 3d context of the browser. Weird things can happen when you are switching contexts for the period of a single animation and indeed there are a lot of complains on the web about flickering in animations. The main suggestion here is to use:

This property removes the backside of your DOM element, which it automatically gets when put into 3D context. From our experience it does have an effect, so it’s definitely worth a try in case of 3D quirks.

Another good practice that reduces glitches is initially having translate3d(0,0,0) on the element to remove the context switch.

CDD and task queue

If you’ve worked with animation code in the past, you might have noticed that it tends to result in nested callbacks. In our company we call it callback driven development – an anti-pattern, which we have tried to get away from by introducing task scheduling system called task queue. The system consists of a task executor that can register and execute tasks in the specified order. Individual tasks either wait for some event to happen or execute code.

To give a bold example, here is what you mind have before you introduce the queue:

And here is what happens after:

The resulting code is not only easier to maintain and reason about, but it also gives you a nice overview of the whole sequence of events. And the best part is that it can be used to sequence anything you want, not only animations.

If you would like to get a library for handling asynchronous code, then search for: javascript flow control library.

Compilation process

Hold on, compiling javascript? Are you mad!

Compiling or building in SPA land means that you apply a set of optimizations to your initial code base to get a better (in many ways) code base as a result without any negative side effects.

As most web developers today, we use gruntjs for this task. It’s a simple nodejs application that we’ve integrated into our CI build system. On each commit it performs its magic and deploys the so-called production version of the game client.

The cool thing about grunt is, of course, the amount of plugins that you can find. And if for some reason you cannot find the one you need, then it is dead easy to write you own. That’s what I also ended up doing ��

Here is our build process at a glance:

1. Grunt-contrib-jshint, grunt-jscs-checker – verify code conventions/quality


2. Grunt-contrib-imagemin – loseless image compression


3. Grunt-css-url-embed – embed images and fonts into CSS files as base64 to disable on-demand loading mechanism inside the browser


4. Grunt-usemin (prepare step) – scan the HTML file for so-called build blocks, that mark what files should be minified (to reduce size) and concatenated into one (to reduce HTTP request count)


5. Grunt-contrib-concat – perform concatenation based of the list compiled by usemin


6. Grunt-contrib-cssmin – perform CSS minification based of the list compiled by usemin


7. Grunt-contrib-uglify – perform JS minification based of the list compiled by usemin


8. Grunt-usemin (perform step) – rewrite the HTML file with references to concatenated and minified assets


9. Grunt-cache-bust – append an “MD5 of content” query string to assets in the HTML file for anti-caching


10. Grunt-contrib-htmlmin – minify HTML files

Compressing assets

Images

As already mentioned, for images we use grunt imagemin plugin, which we have integrated into our build, so that image originals are stored in the code repo and compressed graphics are always part of compiled client.

Sounds

Sound compression is pretty straightforward. Take audacity and play with sampling and bit rates. For devices the quality can be quite low without any real harm.

Fonts

No matter where you get your fonts from use this tool to compress them into .Woff. Results are pretty impressive.

• Use optimal if you don’t care about specific alphabets like cyrillic.


• Use expert if you want to support those alphabets. Make sure that your original font supports those languages in the first place, of course ��

Preloaded assets in HTML

One problem that we’ve came across was that some of the stuff we needed to reference statically in the HTML file and some we had to preload in javascript. Separating assets into several places seemed like a bad idea, since it definitely would have complicated things. The solution was to keep everything in one place – the HTML file. Static assets are referenced as usual and preloaded assets reside in their own special tag:

HTML does not care about them at all, but the preloading component does. It collects those tags and passes URL’s to preloadjs. The cool thing about this approach is that initially it was used only for CSS files, however we did not have to change a thing when it came to sounds. Preloadjs supports them out of the box.

As a nice bonus, we were able to apply our grunt cache busting to preloaded assets as well without any additional work!

Second orientation

One conceptual problem that you always have to deal with when developing a mobile browser game is handling the second orientation. As you cannot lock the orientation in the browser, most games just put a notice for the player to rotate back to the supported orientation. While this seemed like the only feasible option, we somehow felt that something less annoying can be done, so instead of “throwing away” the portrait we turned it to our advantage. The idea is that if the player wants to take the game and lie down on the couch he would still have the ability to play the game without manually locking the screen. To put it simple, we rotate the game by 90° in portrait, so it would be shown as if the orientation was locked to landscape. Not only it allows us to support the so-called couch mode, but also handles the issue of switching to correct orientation, as it intuitively forces the player to rotate the device without the need to read any instructions.

Technically, the task was pretty interesting. We ended up developing an awesome javascript component that knew how to center and scale our game to fit every possible condition. Here are the key CSS and JS features that allowed us to do it:

• Transform-origin, transform – to apply scale() and rotate() with specified pivot point


• Element.Getboundingclientrect() – to get live offset information of the game view element, which can be used to apply counter-offsets for centering

Automated tests

For testing purposes we use jasmine together with jasmine jquery that allows loading your app into the DOM as a fixture and perform asserts on the real thing. The benefit of running tests in the browser is that they can be run on real devices without any additional hacky plugins or add ons. Just open the testing URL and it will do the rest. Nevertheless, to completely relieve us from the manual work we connected a bunch of devices to our CI and scheduled regular test runs on those devices. Thus we got a fully automated testing process on real devices.

Useful stuff to know and use

Lastly, I would like to point our some useful tips and tricks that we’ve gathered during development.

Useful CSS properties

Disables some stuff that is not needed in a game and also adds antialiasing for fonts:

And here is another interesting set of properties that we’ve came across:

We had some very controversial results regarding performance with those, so I am not going to give any suggestions. Take your time, read about them, try them out.

Useful head tags

Do not treat certain long numbers as telephone numbers:

Disable scaling and enable “full screen” mode in iphone through minimal-ui (works since ios 7.1):

Enable saving to home screen in ios:

Icon for home screen in ios:

Disabling scrolling

Scrolling is usually not needed. If you need to enable it, say, only for menu panels, then you can make a condition for preventdefault using, for example, event.Target.

Inertia scrolling

Removing tap delay

In the browser tapping involves a certain delay, since the browser always waits for double tap. There is a neat library called fastclick, which removes it.

Know your visibility toggling options

Knowing how different properties hide your elements can save you a bit of CPU ticks for free. Here are your hiding options:

Completely hides the element and reflows surrounding content. This is the most expensive hider. We use it only in very specific places, where the next one was giving side effects.

• Visibility: hidden

Hides the element visually, while retaining it’s “structural part”. We use this one the most, since in case of absolute positions it behaves exactly like the previous one, but does not force the browser to do reflows.

Hides the element visually, while retaining it’s “structural part” and the ability to receive events. Our tests showed that this one is a tiny bit cheaper than the previous one. It cannot be used everywhere, since it traps events, so we use it only in places that don’t require user input.

To be continued…

Next on our list are android devices. Probably those are going to be a real headache… nevertheless, we are up for the challenge!

Hope you had a great reading and stay tuned for more games from our game studio ��

Slot machine

Slot machine with fruit theme

The game starts with 5000 credits, and you can bet 30, 60 or 90 credits. Click on the bet buttons to make a bet, and then press the "spin" button. The game calculates the winnings based on the bet level, the configuration of the matching pattern, and the value of the matching symbol. If you lose all the credits and go bankrupt, you have to refresh the page to re-start the game.

Slot machines were invented at the end of the 19th century. They became popular in las vegas and in many locations where gambling was allowed. Mechanical machines eventually were superseded by electronic machines that require less maintenance and can be better controlled by the casinos to prevent cheating and to guarantee more consistent profits. Modern slots are programmed with a variety of themes such as storybook fables and even chinese lucky charm symbols to enhance their general appeal. In the era of the internet it is now even possible to play bitcoin casino slots, but there are a number of differences between the online and physical reel versions.

Slot machines are called "fruit machines" in britain and "poker machines" in australia. The casino gambling machines usually have three or more reels that spin when a button is pushed. Slot machines are also called one-armed bandits because slot machines were originally operated by a lever (arm) on the side of the machine, and because they can leave a gambler penniless.

Some slot machines simulate card games and others have special themes. The most popular slot machines in las vegas and atlantic city casinos are wheel of fortune, fort knox, mr. Cashman, little lucy, white ice, haywire, ten times, jackpot party, wild eights, triple cash, wild cherry, double diamond haywire, triple black tie, lucky four leaf clover, pinball, white ice, galileoвђ™s gold, blazing sevens, double diamond, double double diamond, triple diamond, ten times, tabasco, bonus poker, double lucky 7's, sizzling 7's, and blazing 7's.

Javascript slot game

I'm trying to make a slot game using javascript. I need some help here because i'm stuck. I used an array to store the images. I calculate an random number so it takes an image from the array an place it into the src in the HTML file. Then it looks if the images are the same and calculate the ouput in €. If the user clicks on the spin button it had to do the functions.

The eventlistener does't do anything when i click it? Does anybody know why they don't listen to the clicks?

How have you verified that the event listeners are not getting called? Setting breakpoints on the appropriate lines of code?

Have you verified that your element references are correct in the first place? (hint: they're not.)

And why aren't you using jquery to make this all much much simpler?

You answered only the last of my 4 questions.

Set a breakpoint in the code and inspect your variables. Which one is wrong?

If you haven't you should have a quick look over the javascript links (wiki forum at coderanch)
right now you should be interested in the "debugging" section.

For example if you are allowed to use google chrome/chromium as your browser you should be looking at:
chrome devtools overview - google chrome: debugging javascript
and
debugging javascript - google chrome: debugging with breakpoints
so that you can follow bear's advice:

Bear bibeault wrote: set a breakpoint in the code [, step through your code] and inspect your variables. Which one is wrong?[for example, is any variable null or undefined when you don't expect it to be - is there an error message in the javascript console that may indicate that something has gone wrong?]

so, let's see, what we have: javascript can be employed to create a fun, aesthetically pleasing and enticing slot machine game. A designer could pick a theme and base the game around this. For our example we will choose space as the core theme and visual motif. At slot game js