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JavaScript 实现数组的foreach

时间:2016-09-14 19:09:16      阅读:166      评论:0      收藏:0      [点我收藏+]

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Array.prototype.forEach = function (action) {
for (var i = 0; i < this.length; i++) {
action(this[i]);
}
};
/**
* 以jqery 对象的方式迭代对象
* @param {} action
* @returns {}
*/
Array.prototype.forEachJq = function (action) {
for (var i = 0; i < this.length; i++) {
action($(this[i]));
}
};



-----------------------------------------------------------------

// Production steps of ECMA-262, Edition 5, 15.4.4.18 // Reference: http://es5.github.io/#x15.4.4.18 if (!Array.prototype.forEach) { Array.prototype.forEach = function(callback, thisArg) { var T, k; if (this == null) { throw new TypeError(‘ this is null or not defined‘); } // 1. Let O be the result of calling toObject() passing the // |this| value as the argument. var O = Object(this); // 2. Let lenValue be the result of calling the Get() internal // method of O with the argument "length". // 3. Let len be toUint32(lenValue). var len = O.length >>> 0; // 4. If isCallable(callback) is false, throw a TypeError exception. // See: http://es5.github.com/#x9.11 if (typeof callback !== "function") { throw new TypeError(callback + ‘ is not a function‘); } // 5. If thisArg was supplied, let T be thisArg; else let // T be undefined. if (arguments.length > 1) { T = thisArg; } // 6. Let k be 0 k = 0; // 7. Repeat, while k < len while (k < len) { var kValue; // a. Let Pk be ToString(k). // This is implicit for LHS operands of the in operator // b. Let kPresent be the result of calling the HasProperty // internal method of O with argument Pk. // This step can be combined with c // c. If kPresent is true, then if (k in O) { // i. Let kValue be the result of calling the Get internal // method of O with argument Pk. kValue = O[k]; // ii. Call the Call internal method of callback with T as // the this value and argument list containing kValue, k, and O. callback.call(T, kValue, k, O); } // d. Increase k by 1. k++; } // 8. return undefined }; }

JavaScript 实现数组的foreach

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原文地址:http://www.cnblogs.com/micro-chen/p/5873133.html

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