<pre class="shiki github-dark shaku"><code>/** * @param {Promise&lt;any&gt;} promise * @param {() =&gt; void} onFinally * @returns {Promise&lt;any&gt;} */function myFinally(promise, onFinally) { // your code here return promise.then((val) =&gt; Promise.resolve(onFinally()).then(() =&gt; val)) .catch((reason) =&gt; Promise.resolve(onFinally()).then(() =&gt; { throw reason }))}</code></pre>

Steal from MDN :)

Promise.prototype.finally() could be used to run a callback when a promise is settled(either fulfilled or rejected). Notice that the callback passed f…