Number of Recent Calls LeetCode solution in JavaScript

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var RecentCounter = function () {
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  this.arr = [];
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};
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RecentCounter.prototype.ping = function (t) {
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  this.arr.push(t);
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  while (t > this.arr[0] + 3000) {
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    this.arr.shift();
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  }
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  return this.arr.length;
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};