Your JavaScript Library

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Edge of the Web presentation on building your JavaScript library.

Edge of the Web presentation on building your JavaScript library.

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  • I'd really like to find this audio... anyone know where it might be?
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  • Hi,
    I am looking for the audio for this talk.
    Couldn't find it on the Edge of the Web website.
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  • @mangrar That was a whole point of the slide. Of course it works better when I talking next to slide.
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  • About the for loop in the slide 24, don't you think this is better?:

    var arrLength = a.length;
    for(var i=0; i<arrLength ; i++)....

    In your sample, in any iteration you call a.length, with acces to arrLength var you get better performance, I think, because you only call a.length one time.
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Transcript

  • 1. Your JavaScript Library Edge of the Web ’09 Dmitry Baranovskiy
  • 2. http://www.atlassian.com/
  • 3. http://raphaeljs.com/ http://g.raphaeljs.com/
  • 4. Why should I write a library of my own?
  • 5. function trim(str) { return str.replace(/^s+|s+$/g, ""); } function $(id) { return document.getElementById(id); }
  • 6. Low Level
  • 7. High Level
  • 8. Toolbox
  • 9. Widgets
  • 10. Scr i p t ac u l o us gR a ph aël jQuery UI Pr o to t ype ue r y R a ph aël Do j o jQ Ex t
  • 11. API & Functionality
  • 12. Library is the answer. So, what is the question?
  • 13. Library is the answer. So, what is the question?
  • 14. Who is the target? Java, Ruby, PHP, JavaScript…
  • 15. Who is the target? Java, Ruby, PHP, JavaScript…
  • 16. “Everything should be made as simple as possible, but not simpler.” Albert Einstein
  • 17. JavaScript is your friend
  • 18. Performance
  • 19. var a = [1, 2, 3, 4, 5, 6, 7, 8, 9]; for (var i = 0; i < a.length; i++) { a[i] *= 2; } var j = a.length; while (j--) { a[j] *= 2; }
  • 20. function parseColour(colour) { // #XXXXXX var value = parseInt(colour.substring(1), 16); return { r: (value & 0xff0000) >> 16, g: (value & 0xff00) >> 8, b: value & 0xff, }; }
  • 21. var parseColour = (function () { var cache = {}; return function (colour) { if (colour in cache) { return cache[colour]; } // calculation cache[colour] = value; return value; }; })();
  • 22. var parseColour = (function () { var cache = {}, count = []; return function (colour) { if (colour in cache) { return cache[colour]; } // calculation cache[colour] = value; count.push(colour); if (count.length > 1000) { delete cache[count.shift()]; } return value; }; })();
  • 23. JavaScript Rocks! presents... JavaScript Performance Rocks by Thomas Fuchs & Amy Hoy find more awesome JavaScript stuff at http://www.jsrocks.com
  • 24. Animation
  • 25. Bulletproof
  • 26. Global Scope
  • 27. Global Scope Treat it as a public toilet
  • 28. var myLib = { method1: function () {}, method2: function () {}, // ... };
  • 29. var myLib = {}; (function () { var libVariable = 2; myLib.method1 = function () {}; myLib.method2 = function () {}; })();
  • 30. Native Prototypes
  • 31. String.prototype.trim = function () { return this.replace(/^s+|s+$/g, ""); }; Number.prototype.times = function (func) { for (var i = 0; i < this; i++) { func(i); } };
  • 32. Object.prototype
  • 33. for (var value in cache) { this.setAttribute(value, cache[value]); } var horizontal = {left: 1, right: 1}; if (direction in horizontal) { this.horizontal(direction); }
  • 34. Object.prototype.top = 3; // ... for (var value in cache) { this.setAttribute(value, cache[value]); } var horizontal = {left: 1, right: 1}; if (direction in horizontal) { this.horizontal(direction); }
  • 35. Object.prototype.top = 3; // ... for (var value in cache) { if (cache.hasOwnProperty(value)) { this.setAttribute(value, cache[value]); } } var horizontal = {left: 1, right: 1}; if (horizontal.hasOwnProperty(direction)) { this.horizontal(direction); }
  • 36. function isArray(object) { return object && (object instanceof Array); }
  • 37. Beware of <iframe>
  • 38. function isArray(object) { return Object.prototype.toString.call(object) === "[object Array]"; }
  • 39. undefined
  • 40. function setSomething(a) { if (a == undefined) { a = 5; } this.set(a); }
  • 41. var undefined; function setSomething(a) { if (a == undefined) { a = 5; } this.set(a); }
  • 42. function setSomething(a) { this.set(a || 5); }
  • 43. Packaging
  • 44. Minify / Pack / Obfuscate
  • 45. JSMin Dojo ShrinkSafe Packer YUI Compressor
  • 46. 120 Kb jQuery 56 Kb 19 Kb 138 Kb Prototype 80 Kb 24 Kb 121 Kb Raphaël 52 Kb 18 Kb Original Minified GZIP
  • 47. function calculate(value) { if (typeof value == "number") { return parseFloat(value); } if (isArray(value)) { var i = value.length; while (i--) value[i] = parseFloat(value[i]); return value.join(","); } var values = value.split(","), i = values.length; while (i--) values[i] = parseFloat(values[i]); return values.join(","); } 394 b
  • 48. function calculate(c){if(typeof c=="number"){return parseFloat(c);}if(isArray(c)){var b=c.length;while(b--){c[b]=parseFloat(c[b]);}return c.join(",");}var a=c.split(","),b=a.length;while(b--) {a[b]=parseFloat(a[b]);}return a.join(",");} 394 b 235 b
  • 49. function calculate(value) { var parseFloat = parseFloat; if (typeof value == "number") { return parseFloat(value); } if (isArray(value)) { var i = value.length; while (i--) value[i] = parseFloat(value[i]); return value.join(","); } var values = value.split(","), i = values.length; while (i--) values[i] = parseFloat(values[i]); return values.join(","); } 394 b 235 b 427 b
  • 50. function calculate(value) { var parseFloat = parseFloat; if (typeof value == "number") { return parseFloat(value); } if (isArray(value)) { var i = value.length; while (i--) value[i] = parseFloat(value[i]); return value.join(","); } var values = value.split(","), i = values.length; while (i--) values[i] = parseFloat(values[i]); return values.join(","); } 394 b 235 b 427 b
  • 51. function calculate(d){var b=b;if(typeof d=="number") {return b(d);}if(isArray(d)){var c=d.length;while(c--){d[c]=b(d[c]);}return d.join(",");}var a=d.split(","),c=a.length;while(c--) {a[c]=b(a[c]);}return a.join(",");} 394 b 235 b 427 b 216 b
  • 52. element.setAttribute("width", 320);
  • 53. element.setAttribute("width", 320); var setAttribute = function (element, key, value) { element.setAttribute(key, value); } // ... setAttribute(element, "width", 320);
  • 54. element.setAttribute("width", 320); var setAttribute = function (element, key, value) { element.setAttribute(key, value); } // ... setAttribute(element, "width", 320); var setAttribute = "setAttribute"; // ... element[setAttribute]("width", 320);
  • 55. Error Handling
  • 56. function setWidth(width) { width = parseFloat(width); if (isNaN(width)) { handleErrors("‘width’ is not a number"); } } function handleErrors(message) { throw new Error(message); }
  • 57. function update(x, y, width, height) { try { this.setX(x); this.setY(y); this.setWidth(width); this.setHeight(height); } catch (err) { throw new Error("Some error happened… Somewhere."); } }
  • 58. JSLint http://jslint.com/
  • 59. Share the magic
  • 60. Thank You http://dmitry.baranovskiy.com dmitry@baranovskiy.com Icons used with permission of Iconfactory