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Update when.md

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Angelos Chalaris
2018-04-19 20:01:20 +03:00
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parent 3116d19997
commit a9a09a746c
1 changed files with 5 additions and 5 deletions
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snippets/when.md
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@ -1,7 +1,8 @@
### when ### when
Tests a value, `x`, against a predicate function. If `true`, return `fn(x)`. Else, return `x`. Tests a value, `x`, against a predicate function. If `true`, return `fn(x)`. Else, return `x`.
`when(pred, whenTrue)` returns a function expecting `x` for better composability.
Return a function expecting a single value, `x`, that returns the appropriate value based on `pred`.
```js ```js
const when = (pred, whenTrue) => (x) => pred(x) ? whenTrue(x) : x; const when = (pred, whenTrue) => (x) => pred(x) ? whenTrue(x) : x;
@ -12,7 +13,6 @@ const doubleEvenNumbers = when(
(x) => x % 2 === 0, (x) => x % 2 === 0,
(x) => x * 2 (x) => x * 2
); );
doubleEvenNumbers(2); // 4
doubleEvenNumbers(2) // 4 doubleEvenNumbers(1); // 1
doubleEvenNumbers(1) // 1
``` ```