9 lines
220 B
Markdown
9 lines
220 B
Markdown
### Flatten array
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Use `Array.reduce()` to get all elements inside the array and `concat()` to flatten them.
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```js
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const flatten = arr => arr.reduce( (a, v) => a.concat(v), []);
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// flatten([1,[2],3,4]) -> [1,2,3,4]
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```
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