Javascript Nodejs execute function in async parallel with arguments

async-parallel-with-arguments.js

/*
  the trick is in function.bind(null, args ...)
  The functions will be executed independently but the results will be returned all togheter
  in the array in the same order the functions were called
*/
var async = require("async");

function fn1(paramA, paramB, paramC, callback) {
	setTimeout(function(){
		var ret = '(' + paramA + ' ' + paramB + ' ' + paramC + ')';
		callback(null, ret); // err, result
	}, 350);
}
	
function fn2(paramA, paramB, paramC, callback){
	setTimeout(function(){
		var ret = '(' + paramA + ' ' + paramB + ' ' + paramC + ')';
		callback(null, ret); // err, result
	}, 100);
}

async.parallel([fn1.bind(null, 'a', 'b', 'c'), fn2.bind(null, 'A', 'B', 'C')], function(err, result) {
	console.log(result);
});

// with series functions are executed one after the other in the sequence provided
async.series([fn1.bind(null, 'a', 'b', 'c'), fn2.bind(null, 'A', 'B', 'C')], function(err, result) {
	console.log(result);
});