<pre class="shiki github-dark shaku"><code>/** * @param {Array&lt;any&gt;} promises - notice input might have non-Promises * @return {Promise&lt;any[]&gt;} */function all(promises) { return new Promise((res, rej) =&gt; { if(promises.length === 0) return res([]); const result = []; let resolvedPromises = 0; for(let i=0; i&lt;promises.length; i++) { Promise.resolve(promises[i]) .then(val =&gt; { result[i] = val; resolvedPromises++; if(resolvedPromises === promises.length) return res(result); }) .catch(err =&gt; { return rej(err); }); } });}</code></pre>

Easy to understand Promise.all polyfill

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> The Promise.all() method takes an iterable of promises as an input, and returns a single Promise that resolves to an array of the results of the inp…