ensure-async

Wrap an async function and ensure it calls its callback on a later tick of the event loop. Based on async#ensureAsync as module.

Install

npm install ensure-async --save

If you want to use in the browser (powered by Browserify):

bower install ensure-async --save

and later link in your HTML:

<script src="bower_components/ensure-async/dist/ensure-async.js"></script>

Usage

var ensureAsync = require('ensure-async');

function sometimesAsync(arg, callback) {
  if (cache[arg]) {
    return callback(null, cache[arg]); // this would be synchronous!!
  } else {
    doSomeIO(arg, callback); // this IO would be asynchronous
  }
}

// this has a risk of stack overflows if many results are cached in a row
async.mapSeries(args, sometimesAsync, done);

// this will defer sometimesAsync's callback if necessary,
// preventing stack overflows
async.mapSeries(args, ensureAsync(sometimesAsync), done);

API

ensureAsync(fn)

Wrap an async function and ensure it calls its callback on a later tick of the event loop. If the function already calls its callback on a next tick, no extra deferral is added. This is useful for preventing stack overflows (RangeError: Maximum call stack size exceeded) and generally keeping Zalgo contained.

Arguments

• fn - an async function, one that expects a node-style callback as its last argument

Returns a wrapped function with the exact same call signature as the function passed in.

License

MIT © Kiko Beats