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33 lines
1.1 KiB
33 lines
1.1 KiB
3 years ago
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/**
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* @description: 有些函数采用可变数量的参数，或采用一些预期参数
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参数，然后是要操作的可变数量的值
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在…上此帮助程序将所有剩余参数累加到函数的
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参数长度（或显式的“startIndex”）转换为
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最后一个论点。类似于ES6的“rest参数”。
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* @param {Function} func
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* @param {Number} startIndex
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* @return {Function}
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*/
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export default function restArguments(func, startIndex) {
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startIndex = startIndex == null ? func.length - 1 : +startIndex;
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return function () {
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var length = Math.max(arguments.length - startIndex, 0);
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var rest = Array(length);
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var index = 0;
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for (; index < length; index++) {
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rest[index] = arguments[index + startIndex];
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}
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switch (startIndex) {
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case 0: return func.call(this, rest);
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case 1: return func.call(this, arguments[0], rest);
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case 2: return func.call(this, arguments[0], arguments[1], rest);
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}
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var args = Array(startIndex + 1);
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for (index = 0; index < startIndex; index++) {
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args[index] = arguments[index];
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}
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args[startIndex] = rest;
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return func.apply(this, args);
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};
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}
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