48 lines
1.0 KiB
JavaScript
48 lines
1.0 KiB
JavaScript
function setNumIterator() {
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if(!Number.prototype[Symbol.iterator]) {
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Object.defineProperty(
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Number.prototype,
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Symbol.iterator,
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{
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writable: true,
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configurable:true,
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enumerable: false,
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value: function iterator(){
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var i, inc, done = false, top = +this;
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// 正向迭代还是反向迭代？
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inc = 1 * (top < 0 ? -1 : 1);
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console.log(top)
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return {
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// 使迭代器本身成为iterable
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[Symbol.iterator](){return this;},
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next() {
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if(!done) {
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// 初始迭代总是0
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if(i == null) {
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i = 0
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}
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// 正向迭代
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else if(top >= 0) {
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i = Math.min(top, i + inc);
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}
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// 反向迭代
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else {
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i = Math.max(top, i + inc);
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}
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// 本次迭代后结束？
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if (i == top) done = true;
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return {value: i, done: false};
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} else {
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return {done: true};
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}
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}
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}
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}
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}
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)
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}
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}
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setNumIterator()
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for (var i of 3) {
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console.log(i)
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} |