ECMAScript5.js : ES5 準拠のメソッドを定義するJavaScriptライブラリ

ECMAScript5.js

/**
 * ECMAScript5.js (ECMA-262 Edition 5)
 *
 * @version 1.0
 * @author think49
 */

// 15.4.3.2 Array.isArray ( arg )
//
//  1. If Type(arg) is not Object, return false.
//  2. If the value of the [[Class]] internal property of arg is "Array", then return true.
//  3. Return false.
if (typeof Array.isArray !== 'function') {
  Array.isArray = function (arg) {
    if (typeof arg !== 'object') {
      return false;
    }
    if (Object.prototype.toString.call(arg) === '[object Array]') { // Object.prototype.toString outputs [[Class]] internal property
      return true;
    }
    return false;
  };
}


// Array.prototype

(function () {

  // 15.4.4.18 Array.prototype.forEach ( callbackfn [, thisArg] )
  //
  //  1. Let O be the result of calling ToObject passing the this value as the argument.
  //  2. Let lenValue be the result of calling the [[Get]] internal method of O with the argument "length".
  //  3. Let len be ToUint32(lenValue).
  //  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  //  5. If thisArg was supplied, let T be thisArg; else let T be undefined.
  //  6. Let ke be 0.
  //  7. Repeat, white k < len
  //       a. Let Pk be ToString(k)
  //       b. Let kPresent be the result of calling the [[HasProperty]] internal method of O with argument Pk.
  //       c. Let kPresent is true, then
  //            i. Let kValue be the result of calling the [[Get]] internal method of O with argument Pk.
  //           ii. Call the [[Call]] internal method of callbackfn with T as the this value and argument list containing kValue, k, and O.
  //       d. Increase k by 1.
  //  8. Return.
  if (typeof this.forEach !== 'function') {
    this.forEach = function (callbackfn /*, thisArg*/) {
      var thisArg, O, k, len;

      if ('function' !== typeof callbackfn) {
        throw new TypeError(callbackfn + ' is not a function');
      }

      O = Object(this);           // ToObject(this)
      len = Number(O.length);     // ToUint32(lenValue)
      thisArg = arguments[1];

      if (arguments.length < 2) { // for "strict mode"
        thisArg = this;
      }

      for (k = 0, len = O.length; k < len; k++) {
        if (k in O) {
          callbackfn.call(thisArg, O[k], k, O);
        }
      }
    };
  }

  // 15.4.4.17 Array.prototype.some ( callbackfn [ , thisArg ] )
  //
  // 1. Let O be the result of calling ToObject passing the this value as the argument.
  // 2. Let lenValue be the result of calling the [[Get]] internal method of O with the argument "length".
  // 3. Let len be ToUint32(lenValue).
  // 4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  // 5. If thisArg was supplied, let T be thisArg; else let T be undefined.
  // 6. Let k be 0.
  // 7. Repeat, while k < len
  //     a. Let Pk be ToString(k).
  //     b. Let kPresent be the result of calling the [[HasProperty]] internal method of O with argument Pk.
  //     c. If kPresent is true, then
  //         i. Let kValue be the result of calling the [[Get]] internal method of O with argument Pk.
  //        ii. Let testResult be the result of calling the [[Call]] internal method of callbackfn with T as the this value and argument list containing kValue, k, and O.
  //       iii. If ToBoolean(testResult) is true, return true.
  //     d. Increase k by 1.
  // 8. Return false.
  if (typeof this.some !== 'function') {
    this.some = function (callbackfn, thisArg) {
      var O, testResult, k, len;

      if (typeof callbackfn !== 'function') {
        throw new TypeError(callbackfn + ' is not a function');
      }

      O = Object(this);       // ToObject(this)
      len = Number(O.length); // ToUint32(lenValue)

      for (k = 0; k < len; k++) {
        if (k in O) {
          if (thisArg) {      // for "strict mode"
            testResult = callbackfn.call(thisArg, O[k], k, O);
          } else {
            testResult = callbackfn(O[k], k, O); 
          }
          if (testResult) {
            return true;
          }
        }
      }

      return false;
    };
  }

}).call(Array.prototype);


 // String.prototype

(function () {
// Unicode 5.2.0 Property-List ( http://www.unicode.org/Public/5.2.0/ucd/PropList.txt )
/*
var White_Space = {
      Cc: '\u0009-\u000D\u0085',
      Zs: '\u0020\u00A0\u1680\u180E\u2000-\u200A\u202F\u205F\u3000',
      Zl: '\u2028',
      Zp: '\u2029'
    };
*/

  // 15.5.4.20 String.prototype.trim()
  //
  //  1. Call CheckObjectCoercible passing the this value as its argument.
  //  2. Let S be the result of calling ToString, giving it the this value as its argument.
  //  3. Let T be a String value that is a copy of S with both leading and trailing white space removed. The definition of white space is the union of WhiteSpace (*1) and LineTerminator(*2).
  //  4. Return T.
  //
  //  (*1) 7.2 White Space
  //  (*2) 7.3 Line Terminators
  //
  //
  // Unicode 5.2.0 Property-List ( http://www.unicode.org/Public/5.2.0/ucd/PropList.txt )
  //
  // 0009..000D    ; White_Space # Cc   [5] <control-0009>..<control-000D>
  // 0020          ; White_Space # Zs       SPACE
  // 0085          ; White_Space # Cc       <control-0085>
  // 00A0          ; White_Space # Zs       NO-BREAK SPACE
  // 1680          ; White_Space # Zs       OGHAM SPACE MARK
  // 180E          ; White_Space # Zs       MONGOLIAN VOWEL SEPARATOR
  // 2000..200A    ; White_Space # Zs  [11] EN QUAD..HAIR SPACE
  // 2028          ; White_Space # Zl       LINE SEPARATOR
  // 2029          ; White_Space # Zp       PARAGRAPH SEPARATOR
  // 202F          ; White_Space # Zs       NARROW NO-BREAK SPACE
  // 205F          ; White_Space # Zs       MEDIUM MATHEMATICAL SPACE
  // 3000          ; White_Space # Zs       IDEOGRAPHIC SPACE

  if (typeof this.trim !== 'function') {
    this.trim = function () {
      var S              = String(this),
          WhiteSpace     = '\u0009\u000B\u000C\u0020\u00A0\uFEFF',
          Zs             = '\u1680\u180E\u2000-\u200A\u202F\u205F\u3000',  // Unicode 5.2.0 White_Space#Zs besides the WhiteSpace
          LineTerminator = '\u000A\u000D\u2028\u2029',
          whitespaces    = '[' + WhiteSpace + Zs + LineTerminator + ']+';

      return S.replace(new RegExp('^' + whitespaces + '|' + whitespaces + '$', 'g'), '');
    };
  }
}).call(String.prototype);

下記URLに解説があります。

ECMAScript5.js
http://vird2002.s8.xrea.com/javascript/ECMAScript5.html