Use Custom Error in Nodejs with async

async.js, error-handling, javascript, node.js

Solution

You could make a custom error class:

var util    = require('util');
var MyError = function (msg) {
  MyError.super_.apply(this, arguments);
};
util.inherits(MyError, Error);
// use it in your callback
callback(new MyError(), ...);
// check for it
if (err instanceof MyError) {
  ... 
};

Problem

I am using async in a Nodejs application to run a series of functions in series. Each function calls the callback with an err (Can be null) and a result. What I want to do is check in the series callback for a particular error ... a custom error: ``` async.series({ one: function(callback){ // Doing Stuff if(No good) callback(new error('Custom Error'), 'Failure'); else callback(null, 1); }, two: function(callback){ // Doing Stuff if(No good) callback(new error('Custom Error 2'), 'Failure'); else callback(null, 2); } }, function(err, results) { if(err) { // Test for which error was thrown above } }); ``` Any ideas on creating custom error and then testing for them in this context would be great.

Original source