<pre class="shiki github-dark shaku"><code>// This is a JavaScript coding problem from BFE.dev type Flat = (arr: Array&lt;any&gt;, depth?:number) =&gt; Array&lt;any&gt;const flat: Flat = function (arr, depth = 1) { // your imeplementation here if (!Array.isArray(arr)) { return arr; } if (depth &lt; 1) { return Array.isArray(arr) ? [...arr] : arr; } return arr.reduce((cur, val) =&gt; { if (Array.isArray(val)) { return [...cur, ...flat(val, depth-1)]; } else { return [...cur, val] } }, []);}</code></pre>

reduce 一把梭，注意处理边界条件，depth<1和非数组状态

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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()