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

const onetime = require('onetime');
let i = 0;
const foo = onetime(() => ++i);
foo(); //=> 1
foo(); //=> 1
foo(); //=> 1
onetime.callCount(foo); //=> 3
const onetime = require('onetime');
const foo = onetime(() => {}, {throw: true});
foo();
foo();
//=> Error: Function `foo` can only be called once

# API

## onetime(fn, options?)

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.

## onetime.callCount(fn)

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`.

const onetime = require('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

Available as part of the Tidelift Subscription.

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