ECMAScript5

张鑫旭：ECMAScript5介绍

淘宝整理的es5-safe

/*********  It provides the following methods:

Function.prototype.bind
Object.keys
Array.isArray
Array.prototype.forEach
Array.prototype.map
Array.prototype.filter
Array.prototype.every
Array.prototype.some
Array.prototype.reduce
Array.prototype.reduceRight
Array.prototype.indexOf
Array.prototype.lastIndexOf
String.prototype.trim
Date.now

**********/

(function() {

  // es5-safe
  // ----------------
  // Provides compatibility shims so that legacy JavaScript engines behave as
  // closely as possible to ES5.
  //
  // Thanks to:
  //  - http://es5.github.com/
  //  - http://kangax.github.com/es5-compat-table/
  //  - https://github.com/kriskowal/es5-shim
  //  - http://perfectionkills.com/extending-built-in-native-objects-evil-or-not/
  //  - https://gist.github.com/1120592
  //  - https://code.google.com/p/v8/

  var OP = Object.prototype;
  var AP = Array.prototype;
  var FP = Function.prototype;
  var SP = String.prototype;
  var hasOwnProperty = OP.hasOwnProperty;
  var slice = AP.slice;

  /*---------------------------------------*
   * Function
   *---------------------------------------*/

  // ES-5 15.3.4.5
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind
  FP.bind || (FP.bind = function(that) {
    var target = this;

    // If IsCallable(func) is false, throw a TypeError exception.
    if (typeof target !== 'function') {
      throw new TypeError('Bind must be called on a function');
    }

    var boundArgs = slice.call(arguments, 1);

    function bound() {
      // Called as a constructor.
      if (this instanceof bound) {
        var self = createObject(target.prototype);
        var result = target.apply(
            self,
            boundArgs.concat(slice.call(arguments))
        );
        return Object(result) === result ? result : self;
      }
      // Called as a function.
      else {
        return target.apply(
            that,
            boundArgs.concat(slice.call(arguments))
        );
      }
    }

    // NOTICE: The function.length is not writable.
    //bound.length = Math.max(target.length - boundArgs.length, 0);

    return bound;
  });

  // Helpers
  function createObject(proto) {
    var o;

    if (Object.create) {
      o = Object.create(proto);
    }
    else {
      /** @constructor */
      function F() {
      }

      F.prototype = proto;
      o = new F();
    }

    return o;
  }

  /*---------------------------------------*
   * Object
   *---------------------------------------*/
  // http://ejohn.org/blog/ecmascript-5-objects-and-properties/

  // ES5 15.2.3.14
  // http://whattheheadsaid.com/2010/10/a-safer-object-keys-compatibility-implementation
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/keys
  // https://developer.mozilla.org/en/ECMAScript_DontEnum_attribute
  // http://msdn.microsoft.com/en-us/library/adebfyya(v=vs.94).aspx
  Object.keys || (Object.keys = (function() {
    var hasDontEnumBug = !{toString: ''}.propertyIsEnumerable('toString');
    var DontEnums = [
      'toString',
      'toLocaleString',
      'valueOf',
      'hasOwnProperty',
      'isPrototypeOf',
      'propertyIsEnumerable',
      'constructor'
    ];
    var DontEnumsLength = DontEnums.length;

    return function(o) {
      if (o !== Object(o)) {
        throw new TypeError(o + ' is not an object');
      }

      var result = [];

      for (var name in o) {
        if (hasOwnProperty.call(o, name)) {
          result.push(name);
        }
      }

      if (hasDontEnumBug) {
        for (var i = 0; i < DontEnumsLength; i++) {
          if (hasOwnProperty.call(o, DontEnums[i])) {
            result.push(DontEnums[i]);
          }
        }
      }

      return result;
    };

  })());

  /*---------------------------------------*
   * Array
   *---------------------------------------*/
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array
  // https://github.com/kangax/fabric.js/blob/gh-pages/src/util/lang_array.js

  // ES5 15.4.3.2
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/isArray
  Array.isArray || (Array.isArray = function(obj) {
    return OP.toString.call(obj) === '[object Array]';
  });

  // ES5 15.4.4.18
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/array/foreach
  AP.forEach || (AP.forEach = function(fn, context) {
    for (var i = 0, len = this.length >>> 0; i < len; i++) {
      if (i in this) {
        fn.call(context, this[i], i, this);
      }
    }
  });

  // ES5 15.4.4.19
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/map
  AP.map || (AP.map = function(fn, context) {
    var len = this.length >>> 0;
    var result = new Array(len);

    for (var i = 0; i < len; i++) {
      if (i in this) {
        result[i] = fn.call(context, this[i], i, this);
      }
    }

    return result;
  });

  // ES5 15.4.4.20
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/filter
  AP.filter || (AP.filter = function(fn, context) {
    var result = [], val;

    for (var i = 0, len = this.length >>> 0; i < len; i++) {
      if (i in this) {
        val = this[i]; // in case fn mutates this
        if (fn.call(context, val, i, this)) {
          result.push(val);
        }
      }
    }

    return result;
  });

  // ES5 15.4.4.16
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/every
  AP.every || (AP.every = function(fn, context) {
    for (var i = 0, len = this.length >>> 0; i < len; i++) {
      if (i in this && !fn.call(context, this[i], i, this)) {
        return false;
      }
    }
    return true;
  });

  // ES5 15.4.4.17
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/some
  AP.some || (AP.some = function(fn, context) {
    for (var i = 0, len = this.length >>> 0; i < len; i++) {
      if (i in this && fn.call(context, this[i], i, this)) {
        return true;
      }
    }
    return false;
  });

  // ES5 15.4.4.21
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/reduce
  AP.reduce || (AP.reduce = function(fn /*, initial*/) {
    if (typeof fn !== 'function') {
      throw new TypeError(fn + ' is not an function');
    }

    var len = this.length >>> 0, i = 0, result;

    if (arguments.length > 1) {
      result = arguments[1];
    }
    else {
      do {
        if (i in this) {
          result = this[i++];
          break;
        }
        // if array contains no values, no initial value to return
        if (++i >= len) {
          throw new TypeError('reduce of empty array with on initial value');
        }
      }
      while (true);
    }

    for (; i < len; i++) {
      if (i in this) {
        result = fn.call(null, result, this[i], i, this);
      }
    }

    return result;
  });

  // ES5 15.4.4.22
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/reduceRight
  AP.reduceRight || (AP.reduceRight = function(fn /*, initial*/) {
    if (typeof fn !== 'function') {
      throw new TypeError(fn + ' is not an function');
    }

    var len = this.length >>> 0, i = len - 1, result;

    if (arguments.length > 1) {
      result = arguments[1];
    }
    else {
      do {
        if (i in this) {
          result = this[i--];
          break;
        }
        // if array contains no values, no initial value to return
        if (--i < 0)
          throw new TypeError('reduce of empty array with on initial value');
      }
      while (true);
    }

    for (; i >= 0; i--) {
      if (i in this) {
        result = fn.call(null, result, this[i], i, this);
      }
    }

    return result;
  });

  // ES5 15.4.4.14
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/indexOf
  AP.indexOf || (AP.indexOf = function(value, from) {
    var len = this.length >>> 0;

    from = Number(from) || 0;
    from = Math[from < 0 ? 'ceil' : 'floor'](from);
    if (from < 0) {
      from = Math.max(from + len, 0);
    }

    for (; from < len; from++) {
      if (from in this && this[from] === value) {
        return from;
      }
    }

    return -1;
  });

  // ES5 15.4.4.15
  // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Objects/Array/indexOf
  AP.lastIndexOf || (AP.lastIndexOf = function(value, from) {
    var len = this.length >>> 0;

    from = Number(from) || len - 1;
    from = Math[from < 0 ? 'ceil' : 'floor'](from);
    if (from < 0) {
      from += len;
    }
    from = Math.min(from, len - 1);

    for (; from >= 0; from--) {
      if (from in this && this[from] === value) {
        return from;
      }
    }

    return -1;
  });

  /*---------------------------------------*
   * String
   *---------------------------------------*/

  // ES5 15.5.4.20
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/trim
  // http://blog.stevenlevithan.com/archives/faster-trim-javascript
  // http://jsperf.com/mega-trim-test
  SP.trim || (SP.trim = (function() {

    // http://perfectionkills.com/whitespace-deviations/
    var whiteSpaces = [

      '\\s',
      //'0009', // 'HORIZONTAL TAB'
      //'000A', // 'LINE FEED OR NEW LINE'
      //'000B', // 'VERTICAL TAB'
      //'000C', // 'FORM FEED'
      //'000D', // 'CARRIAGE RETURN'
      //'0020', // 'SPACE'

      '00A0', // 'NO-BREAK SPACE'
      '1680', // 'OGHAM SPACE MARK'
      '180E', // '*N VOWEL SEPARATOR'

      '2000-\\u200A',
      //'2000', // 'EN QUAD'
      //'2001', // 'EM QUAD'
      //'2002', // 'EN SPACE'
      //'2003', // 'EM SPACE'
      //'2004', // 'THREE-PER-EM SPACE'
      //'2005', // 'FOUR-PER-EM SPACE'
      //'2006', // 'SIX-PER-EM SPACE'
      //'2007', // 'FIGURE SPACE'
      //'2008', // 'PUNCTUATION SPACE'
      //'2009', // 'THIN SPACE'
      //'200A', // 'HAIR SPACE'

      '200B', // 'ZERO WIDTH SPACE (category Cf)
      '2028', // 'LINE SEPARATOR'
      '2029', // 'PARAGRAPH SEPARATOR'
      '202F', // 'NARROW NO-BREAK SPACE'
      '205F', // 'MEDIUM MATHEMATICAL SPACE'
      '3000' //  'IDEOGRAPHIC SPACE'

    ].join('\\u');

    var trimLeftReg = new RegExp('^[' + whiteSpaces + ']+');
    var trimRightReg = new RegExp('[' + whiteSpaces + ']+$');

    return function() {
      return String(this).replace(trimLeftReg, '').replace(trimRightReg, '');
    }

  })());

  /*---------------------------------------*
   * Date
   *---------------------------------------*/

  // ES5 15.9.4.4
  // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/now
  Date.now || (Date.now = function() {
    return +new Date;
  });

})();