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| // This version cannot protect its internal | |
| // data from external tampering. | |
| function Sampler(expect) { | |
| this.values = new Array(); | |
| this.expect = expect; | |
| } | |
| Sampler.prototype.add = function(value) { | |
| var length = this.values.length; | |
| if (length === this.expect) { | |
| this.values.shift(); | |
| } | |
| this.values.push(value); | |
| return this; | |
| }; | |
| Sampler.prototype.average = function() { | |
| var value = 0; | |
| if (this.values.length === this.expect) { | |
| for (var i = 0; i < this.expect; i++) { | |
| value += this.values[i] | 0; | |
| } | |
| return Math.round(value / this.expect); | |
| } | |
| return null; | |
| }; | |
| Sampler.prototype.reset = function() { | |
| this.values.length = 0; | |
| }; | |
| module.exports = Sampler; |
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| let priv = new WeakMap(); | |
| export class Sampler { | |
| constructor(expect) { | |
| let list = new Array(); | |
| priv.set(this, { list, expect }); | |
| } | |
| add(value) { | |
| let stored = priv.get(this); | |
| if (stored.list.length === stored.expect) { | |
| stored.list.shift(); | |
| } | |
| stored.list.push(value); | |
| return this; | |
| } | |
| average() { | |
| let stored = priv.get(this); | |
| let value = 0; | |
| if (stored.list.length === stored.expect) { | |
| for (let n of stored.list) { | |
| value += n | 0; | |
| } | |
| return Math.round(value / stored.expect); | |
| } | |
| return null; | |
| } | |
| reset() { | |
| priv.get(this).list.length = 0; | |
| } | |
| } |
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| var sampler = new Sampler(5); | |
| sampler.add(10); | |
| sampler.add(20); | |
| sampler.add(15); | |
| sampler.add(18); | |
| sampler.add(19); | |
| console.log(sampler.average() === 16); | |
| sampler.reset(); | |
| sampler.add(0); | |
| sampler.add(9); | |
| sampler.add(18); | |
| sampler.add(27); | |
| sampler.add(36); | |
| console.log(sampler.average() === 18); | |
| sampler.reset(); | |
| sampler.add(1); | |
| sampler.add(1); | |
| sampler.add(1); | |
| sampler.add(1); | |
| sampler.add(1); | |
| console.log(sampler.average() === 1); | |
| sampler.reset(); | |
| sampler.add(2); | |
| sampler.add(4); | |
| sampler.add(6); | |
| sampler.add(8); | |
| sampler.add(10); | |
| // This value will result in the first | |
| // value (2) being shifted off. | |
| sampler.add(1000); | |
| console.log(sampler.average() === 206); | |
| sampler.reset(); |
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