25 lines
755 B
Markdown
25 lines
755 B
Markdown
---
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title: pickBy
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tags: object,intermediate
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firstSeen: 2018-01-19T13:23:45+02:00
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lastUpdated: 2020-10-22T20:24:04+03:00
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---
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Creates an object composed of the properties the given function returns truthy for.
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- Use `Object.keys(obj)` and `Array.prototype.filter()`to remove the keys for which `fn` returns a falsy value.
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- Use `Array.prototype.reduce()` to convert the filtered keys back to an object with the corresponding key-value pairs.
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- The callback function is invoked with two arguments: (value, key).
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```js
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const pickBy = (obj, fn) =>
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Object.keys(obj)
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.filter(k => fn(obj[k], k))
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.reduce((acc, key) => ((acc[key] = obj[key]), acc), {});
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```
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```js
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pickBy({ a: 1, b: '2', c: 3 }, x => typeof x === 'number');
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// { 'a': 1, 'c': 3 }
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```
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