<pre class="shiki github-dark shaku"><code>/** * @param { Array } arr * @param { number } depth * @returns { Array } */function flat(arr, depth = 1) { // your imeplementation here var recursive = (arr, depth)=&gt;{ if(depth === 0) { return arr } let res = [] for(let i=0; i &lt; arr.length; i++){ if(Array.isArray(arr[i])){ res.push(...recursive(arr[i], depth-1)) } else{ res.push(arr[i]) } } return res } return recursive(arr, depth)}</code></pre>

This is my accepted solution

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There is already Array.prototype.flat() in JavaScript (ES2019), which reduces the nesting of Array. Please implement your own. const arr = [1, [2], [3…

implement it by yourself

4. implement basic throttle()

2. implement curry() with placeholder support

3. implement Array.prototype.flat()