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copied!<p>I came across the <a href="https://developer.mozilla.org/en-US/docs/Web/API/window.performance" rel="nofollow">performance API</a>. What you're looking for is probably <code>Performance.now()</code>, which will give you microsecond percision.</p> <blockquote> <p>The <strong><code>Performance.now()</code></strong> method returns a <a href="https://developer.mozilla.org/en-US/docs/Web/API/DOMHighResTimeStamp" rel="nofollow">DOMHighResTimeStamp</a>, measured in milliseconds, accurate to one thousandth of a millisecond equal to the number of milliseconds since the <a href="https://developer.mozilla.org/en-US/docs/Web/API/PerformanceTiming.navigationStart" rel="nofollow">PerformanceTiming.navigationStart</a> property and the call to the method <a href="https://developer.mozilla.org/en-US/docs/Web/API/Performance.now" rel="nofollow">(source).</a></p> </blockquote> <p>The example MDN provides is:</p> <pre><code>var t0 = performance.now(); doSomething(); var t1 = performance.now(); console.log("Call to doSomething took " + (t1 - t0) + " milliseconds.") </code></pre> <p>A function you could use to test the performance of a specific short piece of code multiple times, you could use the following:</p> <pre><code>/** * Finds the performance for a given function * function fn the function to be executed * int n the amount of times to repeat * return array [time elapsed for n iterations, average execution frequency (executions per second)] */ function getPerf(fn, n) { var t0, t1; t0 = performance.now(); for (var i = 0; i < n; i++) { fn(i) } t1 = performance.now(); return [t1 - t0, repeat * 1000 / (t1 - t0)]; } </code></pre> <p>Which returns the amount of time a single execution of <code>fn(i)</code> takes in milliseconds, and the frequency of execution (executions per second). The higher the <code>n</code> value, the more precision this has, but the longer it takes to test. The argument <code>i</code> can be included in the function to be tested, which contains the current iteration of the function. </p>

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