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38 lines
757 B
38 lines
757 B
4 years ago
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# `countBy()`
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The countBy method counts the occurences of values in the collection. By default, the method counts the occurrences of every element:
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```js
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const collection = collect([1, 2, 2, 2, 3]);
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const counted = collection.countBy();
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counted.all();
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// {
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// 1: 1,
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// 2: 3,
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// 3: 1,
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// }
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```
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However, you pass a callback to the countBy method to count all items by a custom value:
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```js
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const collection = collect([
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'mohamed.salah@gmail.com',
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'sadio.mane@yahoo.com',
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'roberto.firmino@gmail.com',
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]);
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const counted = collection.countBy(email => email.split('@')[1]);
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counted.all();
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// {
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// 'gmail.com': 2,
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// 'yahoo.com': 1,
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// }
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```
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[View source on GitHub](https://github.com/ecrmnn/collect.js/blob/master/src/methods/countBy.js)
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