15 lines
578 B
Markdown
15 lines
578 B
Markdown
### findKey
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Returns the first key that satisfies the provided testing function. Otherwise `undefined` is returned.
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Use `Object.keys(obj)` to get all the properties of the object, `Array.find()` to test the provided function for each key-value pair. The callback receives three arguments - the value, the key and the object.
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```js
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const findKey = (obj, fn) =>
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Object.keys(obj).find(key => fn(obj[key], key, obj));
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```
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```js
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findKey({barney: { age: 36, active: true }, fred: { age: 40, active: false }, pebbles: { age: 1, active: true }}, o => o['active']); // 'barney'
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```
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