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# onetime [![Build Status](https://travis-ci.org/sindresorhus/onetime.svg?branch=master)](https://travis-ci.org/sindresorhus/onetime)
> Only call a function once
When called multiple times it will return the return value from the first call.
*Unlike the module [once](https://github.com/isaacs/once), this one isn't naughty extending `Function.prototype`.*
## Install
```
$ npm install --save onetime
```
## Usage
```js
let i = 0;
const foo = onetime(() => i++);
foo(); //=> 0
foo(); //=> 0
foo(); //=> 0
```
## API
### onetime(function, [shouldThrow])
#### function
Type: `function`
Function that should only be called once.
#### shouldThrow
Type: `boolean`
Default: `false`
![](screenshot-shouldthrow.png)
Set to `true` if you want it to fail with a nice and descriptive error when called more than once.
## License
MIT © [Sindre Sorhus](http://sindresorhus.com)