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ES6 Iterator Timing
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| function foo() { | |
| 'use strict'; | |
| class MyArrayIterator { | |
| constructor(source) { | |
| this._index = 0; | |
| this._source = source; | |
| } | |
| next() { | |
| if (this._index >= this._source.length) { | |
| return undefined; | |
| } | |
| return this._source[this._index++]; | |
| } | |
| } | |
| class ESArrayIterator { | |
| constructor(source) { | |
| this._index = 0; | |
| this._source = source; | |
| } | |
| [Symbol.iterator]() { | |
| return this; | |
| } | |
| next() { | |
| if (this._index >= this._source.length) { | |
| return { done: true }; | |
| } | |
| return { done: false, value: this._source[this._index++] }; | |
| } | |
| } | |
| function mySum(it) { | |
| let v; | |
| let r = 0; | |
| while ((v = it.next()) !== undefined) { | |
| r += v; | |
| } | |
| return r; | |
| } | |
| function esSum(it) { | |
| let r = 0; | |
| for (let v of it) { | |
| r += v; | |
| } | |
| return r; | |
| } | |
| function esSum2(it) { | |
| let r = 0; | |
| while (true) { | |
| let { done, value } = it.next(); | |
| if (done) { | |
| return r; | |
| } | |
| r += value; | |
| } | |
| } | |
| function makeData() { | |
| let data = []; | |
| for (let i = 0; i < 1000000; ++i) { | |
| data.push(Math.random()); | |
| } | |
| return data; | |
| } | |
| var data = makeData(); | |
| function myTiming() { | |
| let it = new MyArrayIterator(data); | |
| let t1 = performance.now(); | |
| let r = mySum(it); | |
| let t2 = performance.now(); | |
| return [r, t2 - t1]; | |
| } | |
| function esTiming() { | |
| let it = new ESArrayIterator(data); | |
| let t1 = performance.now(); | |
| let r = esSum(it); | |
| let t2 = performance.now(); | |
| return [r, t2 - t1]; | |
| } | |
| function esTiming2() { | |
| let it = new ESArrayIterator(data); | |
| let t1 = performance.now(); | |
| let r = esSum2(it); | |
| let t2 = performance.now(); | |
| return [r, t2 - t1]; | |
| } | |
| return {myTiming, esTiming, esTiming2}; | |
| } | |
| let things = foo(); | |
| myTiming = things.myTiming; | |
| esTiming = things.esTiming; | |
| esTiming2 = things.esTiming2; |
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