And a video explaining it <a href="https://www.youtube.com/watch?v=KjoJNLQ-WDY">https://www.youtube.com/watch?v=KjoJNLQ-WDY</a>
<pre class="shiki github-dark shaku"><code>/** * @param { any[] } arr * @returns { ? } */function wrap(arr) { // your code here return new Proxy(arr, { get(target, prop) { // if used ast iterable if (prop === Symbol.iterator) { return target[prop].bind(target) } let index = parseInt(prop, 10) if (index &lt; 0) { index += arr.length return target[index] } return target[prop] }, set(target, prop, value) { let index = parseInt(prop, 10) if (index &lt; 0) { index += arr.length target[index] = value if (index &lt; 0) { throw new Error('index is overflow') } return true } target[prop] = value return true } })}</code></pre>

Proxy is so cool!

Python supports negative list index , while JavaScript doesn't. Can you write a wrapper function to make negative array index possible? const original…