58 строки
1.7 KiB
JavaScript
58 строки
1.7 KiB
JavaScript
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// Production steps of ECMA-262, Edition 5, 15.4.4.18
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// Reference: http://es5.github.io/#x15.4.4.18
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if (!Array.prototype.forEach) {
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Array.prototype.forEach = function(callback, thisArg) {
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var T, k;
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if (this == null) {
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throw new TypeError(' this is null or not defined');
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}
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// 1. Let O be the result of calling ToObject passing the |this| value as the argument.
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var O = Object(this);
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// 2. Let lenValue be the result of calling the Get internal method of O with the argument "length".
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// 3. Let len be ToUint32(lenValue).
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var len = O.length >>> 0;
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// 4. If IsCallable(callback) is false, throw a TypeError exception.
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// See: http://es5.github.com/#x9.11
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if (typeof callback !== "function") {
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throw new TypeError(callback + ' is not a function');
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}
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// 5. If thisArg was supplied, let T be thisArg; else let T be undefined.
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if (arguments.length > 1) {
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T = thisArg;
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}
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// 6. Let k be 0
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k = 0;
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// 7. Repeat, while k < len
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while (k < len) {
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var kValue;
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// a. Let Pk be ToString(k).
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// This is implicit for LHS operands of the in operator
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// b. Let kPresent be the result of calling the HasProperty internal method of O with argument Pk.
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// This step can be combined with c
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// c. If kPresent is true, then
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if (k in O) {
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// i. Let kValue be the result of calling the Get internal method of O with argument Pk.
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kValue = O[k];
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// ii. Call the Call internal method of callback with T as the this value and
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// argument list containing kValue, k, and O.
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callback.call(T, kValue, k, O);
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}
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// d. Increase k by 1.
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k++;
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}
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// 8. return undefined
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};
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}
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