Debounce asynchronous functions


Debounce asynchronous functions.

Debouncing means that given function is only run after no calls to it have happened for x milliseconds. With functions that do asynchronous work, i.e. not finish in the same tick, you also want no calls to happen while the function is currently running - limit the concurrency to one - and rerun with new arguments afterwards.

var debounce = require('async-debounce');
function async(numdone) {
  console.log('start', num);
  setTimeout(function() {
    console.log('done', num);
  }, 200);
var debounced = debounce(async, 50);
console.log('call 1'); debounced(1);
setTimeout(function() { console.log('call 2'); debounced(2) }, 100);
setTimeout(function() { console.log('call 3'); debounced(3) }, 200);

And in the output you can see that the function is run at max once at a time and if the debounce triggers while the function is still running, it will be queued.

$ node example.js
call 1
start 1
call 2
call 3
done 1
start 3
done 3

Install with npm:

$ npm install async-debounce

Install with component(1):

$ component install juliangruber/async-debounce

Returns a decorated version of fn that when called calls fn only when no further calls have happended for interval milliseconds and if it's not currently running. When it's done running and a call has happened while it was still running, it's called again with latest arguments.