onetime

> Ensure a function is only called once

When called multiple times it will return the return value from the first call.

Unlike the module once, this one isn't naughty and extending Function.prototype.

Install

``
$ npm install onetime
`

Usage

`js
import onetime from 'onetime';

let index = 0;

const foo = onetime(() => ++index);

foo(); //=> 1
foo(); //=> 1
foo(); //=> 1

onetime.callCount(foo); //=> 3
`

`js
import onetime from 'onetime';

const foo = onetime(() => {}, {throw: true});

foo();

foo();
//=> Error: Function foo can only be called once
`

API

$3

Returns a function that only calls fn once.

#### fn

Type: Function

Function that should only be called once.

#### options

Type: object

##### throw

Type: boolean\
Default: false

Throw an error when called more than once.

$3

Returns a number representing how many times fn has been called.

Note: It throws an error if you pass in a function that is not wrapped by onetime.

`js
import onetime from 'onetime';

const foo = onetime(() => {});

foo();
foo();
foo();

console.log(onetime.callCount(foo));
//=> 3
`

#### fn

Type: Function`

Function to get call count from.

onetime for enterprise

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