30 lines
817 B
Markdown
30 lines
817 B
Markdown
---
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title: partition
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tags: array,object,intermediate
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---
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Groups the elements into two arrays, depending on the provided function's truthiness for each element.
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- Use `Array.prototype.reduce()` to create an array of two arrays.
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- Use `Array.prototype.push()` to add elements for which `fn` returns `true` to the first array and elements for which `fn` returns `false` to the second one.
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```js
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const partition = (arr, fn) =>
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arr.reduce(
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(acc, val, i, arr) => {
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acc[fn(val, i, arr) ? 0 : 1].push(val);
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return acc;
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},
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[[], []]
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);
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```
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```js
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const users = [
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{ user: 'barney', age: 36, active: false },
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{ user: 'fred', age: 40, active: true },
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];
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partition(users, o => o.active);
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// [[{ 'user': 'fred', 'age': 40, 'active': true }],[{ 'user': 'barney', 'age': 36, 'active': false }]]
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```
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