onetime

Ensure a function is only called once

Programming language: JavaScript

License: MIT License

Tags: Miscellaneous     Prevent     Function     Call     Single     One     Once     called     fn     func     onetime    

Latest version: v5.1.2

README

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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