Performance, Games, and Distributed Testing in JavaScript

Measuring Performance, JavaScript Games, and Distributed Testing John Resig http://ejohn.org - http://twitter.com/jeresig

Measuring Performance

Analyzing Performance Optimizing performance is a huge ✦ concern: Faster code = happy users! Measure execution time ✦ Loop the code a few times ✦ Measure the diﬀerence: ✦ ✦ (new Date).getTime();

Stack Profiling jQuery Stack Profiler ✦ Look for problematic methods and plugins ✦ http://ejohn.org/blog/deep-profiling- ✦ jquery-apps/

Accuracy of JavaScript Time We’re measuring the performance of JavaScript from within JavaScript! http://ejohn.org/blog/accuracy-of-javascript-time/

15ms intervals ONLY! Error Rate of 50-750%!

Performance Tools How can we get good numbers? ✦ We have to go straight to the source: Use ✦ the tools the browsers provide. Tools: ✦ ✦ Firebug Profiler ✦ Safari Profiler ✦ (Part of Safari 4) ✦ IE 8 Profiler

Firebug Proﬁler

Safari 4 Proﬁler

IE 8 Proﬁler

FireUnit A simple JavaScript test suite embedded in ✦ Firebug. http://ﬁreunit.org/ ✦

FireUnit Profile Data { fireunit.getProfile(); quot;timequot;: 8.443, quot;callsquot;: 611, quot;dataquot;:[ { quot;namequot;:quot;makeArray()quot;, quot;callsquot;:1, quot;percentquot;:23.58, quot;ownTimequot;:1.991, quot;timequot;:1.991, quot;avgTimequot;:1.991, quot;minTimequot;:1.991, quot;maxTimequot;:1.991, quot;fileNamequot;:quot;jquery.js (line 2059)quot; }, // etc. http://ejohn.org/blog/function-call-profiling/ ]}

Complexity Analysis Analyze complexity rather than raw time ✦ jQuery Call Count Proﬁler (uses FireUnit) ✦ Method Calls Big-O .addClass(quot;testquot;); 542 6n .addClass(quot;testquot;); 592 6n .removeClass(quot;testquot;); 754 8n .removeClass(quot;testquot;); 610 6n .css(quot;colorquot;, quot;redquot;); 495 5n .css({color: quot;redquot;, border: quot;1px 887 9n solid redquot;}); .remove(); 23772 2n+n2 .append(quot;<p>test</p>quot;); 307 3n

Complexity Analysis Reducing call count helps to reduce ✦ complexity Results for 1.3.3: ✦ Method Calls Big-O .remove(); 298 3n .html(quot;<p>test</p>quot;); 507 5n .empty(); 200 2n http://ejohn.org/blog/function-call-proﬁling/

Why JavaScript Games Are HARD to Build

Browser-Based Games No installation required ✦ (Will be able to play at work!) ✦

Why not Flash? JavaScript works everywhere ✦ ✦ Desktop ✦ iPhone / Mobile Device ✦ Wii ✦ OLPC JavaScript is an open technology ✦

Goals of a game Should be Multiplayer ✦ Can’t be casually cheated ✦ Work well everywhere ✦ Addictive ✦

Why Multiplayer? Incredibly addictive ✦ ✦ No longer “alone” ✦ Enticed to continue playing

3 Styles of Games Strategy ✦ Intelligence ✦ Accuracy ✦

Strategy Games Require a lot of time to think ✦ Generally last over a couple hours or days ✦ Replayability ✦ Hard to cheat ✦

WarFish http://warﬁsh.net/ ✦

Nile Online http://www.playnileonline.com/ ✦

Strategy Games Very server-side heavy ✦ ✦ Most logic hidden from the user Hard to cheat ✦ ✦ Casual cheaters can’t change values ✦ Dedicated cheaters have to write full AI

Intelligence Games Player’s intelligence/knowledge challenged ✦ Games could be quick or slow-paced ✦ Easy to cheat ✦ ✦ Casual cheaters can open dictionary / encyclopedia for answers

Word Twist http://wordtwist.org/ ✦

Babble http://playbabble.com/ ✦

Iron Sudoku http://ironsudoku.com/ ✦

Speed/Accuracy Games Require low latency ✦ Fast-paced and addictive ✦ JavaScript completely fails ✦ ✦ Garbage Collection cycles freeze the browser None, or few, Accuracy-centric JavaScript ✦ games Experienced coders can easily cheat ✦ ✦ (A bot to hit the keys at the right time)

Guitar Hero http://ejohn.org/apps/hero/

Guitar Hero Heavily dependent upon accuracy ✦ ✦ (Hit the right notes at the right time) Garbage collection cycles absolutely kill ✦ the game Rendering the play area is also diﬃcult ✦ ✦ And impossible in all browsers. ✦ (Use HTML 5 Canvas Element)

Failures on All Ends Strategy: Slow, secret server-side code ✦ Intelligence: Easily cheatable ✦ Accuracy: Too hard to implement ✦ Optimal solution would be a combination ✦ of the above. JavaScript games can’t be like other games, ✦ have to be unique.

What can make a fun game? Quick play ✦ Points ✦ High Scores ✦ Head-to-head competition ✦

Wordsplay Real-time Boggle ✦ Head-to-head with other players ✦ http://www.wordsplay.net/

Tringo Tetris + Bingo (based on a Second Life ✦ game) http://ejohn.org/tringo/

DeepLeap Fast-paced Scrabble-like game ✦ Speed + Intelligence + Strategy ✦ http://deepleap.org/

vs. Cheating All words are recorded with exact time ✦ information Game is “played back” on the server to ✦ verify score integrity using Server-Side JS This data can be used to simulate a multi- ✦ player experience!

DeepLeap Works in multiple languages ✦ ✦ Dictionaries pulled from OpenOﬃce, can build a Spanish version in < 5sec Players can challenge each other head-to- ✦ head Score multiplier (carry over from Guitar ✦ Hero)

Distributed Testing

Choose Your Browsers

Cost / Beneﬁt IE 7 IE 6 FF 3 Safari 3 Opera 9.5 Cost Benefit Draw a line in the sand.

Graded Support Yahoo Browser Compatibility

Browser Support Grid IE Firefox Safari Opera Chrome Previous 6.0 2.0 3.0 9.5 Current 7.0 3.0 3.2 9.6 1.0 Next 8.0 3.1 4.0 10.0 2.0 jQuery Browser Support

Browser Support Grid IE Firefox Safari Opera Chrome Previous 3.0 9.5 6.0 2.0 Current 7.0 3.0 3.2 9.6 1.0 Next 8.0 3.1 4.0 2.0 10.0 jQuery 1.3 Browser Support

The Scaling Problem The Problem: ✦ ✦ jQuery has 6 test suites ✦ Run in 11 browsers ✦ (Not even including multiple platforms!) All need to be run for every commit, ✦ patch, and plugin. JavaScript testing doesn’t scale well. ✦

Distributed Testing Hub server ✦ Clients connect and help run tests ✦ A simple JavaScript client that can be run ✦ in all browsers ✦ Including mobile browsers! ✦ TestSwarm

FF 3.5 FF 3.5 FF 3.5 IE 6 IE 6 FF 3 IE 6 Op 9 FF 3 IE 7 TestSwarm IE 7 Test Suite Test Suite Test Suite

Manual Testing Push tests to users who follow pre-deﬁned ✦ steps Answer ‘Yes’/’No’ questions which are ✦ pushed back to the server. An eﬀective way to distribute manual test ✦ load to dozens of clients.

TestSwarm.com Incentives for top testers (t-shirts, books) ✦ Will be opening for alpha testing very soon ✦ Help your favorite JavaScript library ✦ become better tested! http://testswarm.com ✦

Questions Contact: ✦ ✦ John Resig ✦ http://ejohn.org/ ✦ http://twitter.com/jeresig

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Performance, Games, and Distributed Testing in JavaScript

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