26 lines
857 B
Markdown
26 lines
857 B
Markdown
---
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title: Omit object properties based on function
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tags: object
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expertise: intermediate
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cover: blog_images/arrow-functions.jpg
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firstSeen: 2018-01-19T13:23:45+02:00
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lastUpdated: 2020-10-21T21:54:53+03:00
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---
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Omits the key-value pairs corresponding to the keys of the object for which the given function returns falsy.
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- Use `Object.keys()` and `Array.prototype.filter()` to remove the keys for which `fn` returns a truthy 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 omitBy = (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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omitBy({ a: 1, b: '2', c: 3 }, x => typeof x === 'number'); // { b: '2' }
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```
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