8ee50178f3
Correct: `Array.from()` (it’s a static method) Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method) This patch uses the common `#` syntax to denote `.prototype.`.
16 lines
388 B
Markdown
16 lines
388 B
Markdown
### deepFlatten
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Deep flattens an array.
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Use recursion.
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Use `Array.prototype.concat()` with an empty array (`[]`) and the spread operator (`...`) to flatten an array.
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Recursively flatten each element that is an array.
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```js
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const deepFlatten = arr => [].concat(...arr.map(v => (Array.isArray(v) ? deepFlatten(v) : v)));
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```
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```js
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deepFlatten([1, [2], [[3], 4], 5]); // [1,2,3,4,5]
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```
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