JavaScript 实现数组的foreach

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
};
}
上一篇:【spring源码学习】spring集成orm数据框架


下一篇:如何实现在H5里调起高德地图APP?(上)