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xen-orchestra/@vates/predicates/README.md
2022-02-10 16:55:15 +01:00

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# @vates/predicates
[![Package Version](https://badgen.net/npm/v/@vates/predicates)](https://npmjs.org/package/@vates/predicates) ![License](https://badgen.net/npm/license/@vates/predicates) [![PackagePhobia](https://badgen.net/bundlephobia/minzip/@vates/predicates)](https://bundlephobia.com/result?p=@vates/predicates) [![Node compatibility](https://badgen.net/npm/node/@vates/predicates)](https://npmjs.org/package/@vates/predicates)
> Utilities to compose predicates
## Install
Installation of the [npm package](https://npmjs.org/package/@vates/predicates):
```
> npm install --save @vates/predicates
```
## Usage
`undefined` predicates are ignored and `undefined` is returned if all predicates are `undefined`, this permits the most efficient composition:
```js
const compositePredicate = every(undefined, some(predicate2, undefined))
// ends up as
const compositePredicate = predicate2
```
Predicates can also be passed wrapped in an array:
```js
const compositePredicate = every([predicate1, some([predicate2, predicate3])])
```
`this` and all arguments are passed to the nested predicates.
### `every(predicates)`
> Returns a predicate that returns `true` iff every predicate returns `true`.
```js
const isBetween3And7 = every(
n => n >= 3,
n => n <= 7
)
isBetween3And10(0)
// → false
isBetween3And10(5)
// → true
isBetween3And10(10)
// → false
```
### `some(predicates)`
> Returns a predicate that returns `true` iff some predicate returns `true`.
```js
const isAliceOrBob = some(
name => name === 'Alice',
name => name === 'Bob'
)
isAliceOrBob('Alice')
// → true
isAliceOrBob('Bob')
// → true
isAliceOrBob('Oscar')
// → false
```
## Contributions
Contributions are _very_ welcomed, either on the documentation or on
the code.
You may:
- report any [issue](https://github.com/vatesfr/xen-orchestra/issues)
you've encountered;
- fork and create a pull request.
## License
[ISC](https://spdx.org/licenses/ISC) © [Vates SAS](https://vates.fr)