promise-limit-one

Wrap a function so if called multiple times, only one call runs simultaneously.

Note: This package replaces promise-not-if-busy, which is now deprecated.

Installation

npm install promise-limit-one

Usage

const limitOne = require('promise-limit-one')

const longOperation = () => new Promise(function (resolve) {
  console.log('Executing a long operation...')
  setTimeout(resolve, 100)
})

const wrapped = limitOne(longOperation)

wrapped() // will print "Executing..."
wrapped() // will do nothing

setTimeout(function () {
  wrapped() // will print "Executing..." again
}, 150)

API

limitOne(fn, err)

Creates a function that when called multiple times will call fn and wait for it to finish before calling fn again.

If err is supplied and the function is running, any new call will reject with err.

Params

fn: Function that returns a promise.

Returns

A function that wraps fn up. It will return a promise that will resolve to the result of calling fn. While fn is busy, it will resolve to the pending promise.

License

MIT