<code>O(n**2)</code> total: <code>O(n)</code> operation to find the earliest task every time. Not very efficient. However, in real implementations, a priority queue <code>O(n logn)</code> would be more appropriate.
<pre class="shiki github-dark shaku"><code>class FakeTimer { install() { // replace window.setTimeout, window.clearTimeout, Date.now // with your implementation this.setTimeoutOriginal = window.setTimeout; this.clearTimeoutOriginal = window.clearTimeout; this.dateNowOriginal = Date.now; this.seconds = 0; this.tasks = new Map(); window.setTimeout = (fn, delay) =&gt; { const timerId = this.tasks.size + 1; this.tasks.set(timerId, [fn, delay + this.seconds]); return timerId; }; window.clearTimeout = (id) =&gt; { this.tasks.delete(id); } Date.now = () =&gt; this.seconds; } uninstall() { // restore the original implementation of // window.setTimeout, window.clearTimeout, Date.now window.setTimeout = this.setTimeoutOriginal; window.clearTimeout = this.clearTimeoutOriginal; Date.now = this.dateNowOriginal; } tick() { // run the scheduled functions without waiting while (this.tasks.size) { // Pick the earliest task let earliestTaskId; for (const [timerId, [, delay]] of this.tasks) { if (earliestTaskId === undefined || this.tasks.get(earliestTaskId)[1] &gt; delay) { earliestTaskId = timerId; } } const [fn, delay] = this.tasks.get(earliestTaskId); this.seconds = delay; this.tasks.delete(earliestTaskId); fn(); } }}</code></pre>

My accepted solution. O(n**2), but ok for a Javascript excercise

setTimeout adds task in to a task queue to be handled later, the time actually is no accurate. (Event Loop). This is OK in general web application, bu…