Simple example showing how to chain functions similar to how middleware is chained in express.js

chainMiddleware.js

// simple example of how to create a function that calls a middleware chain, similar to express middleware

var req = {type: "req"};
var res = {type: "res"};

// 3 middlewares
var first = function(req, res, next) {
	req.first = true; //easy way to verify that all have been executed
	res.first = true;
	return next();
}

var second = function(req, res, next) {
	req.second = true;
	res.second = true;
	return next();
}

// this one is last
var last = function(req, res) {
	console.log('End of middleware reached');
	console.log('req', req);
	console.log('res', res);
}


// Starts with last function in the array, and binds params (req,res) and "next" fn if available
// Iterates through fns array backwards binds to the next until it reaches the beginning of the fns array
//  @params you want to pass to each one
//  @functions in the middleware chain
//  @returns a function that starts it all
function chainMiddleware(params, ...fns) {
	return fns.reduceRight(function(prev, curr) {
		return curr.bind(null, ...params, prev); // bind req,res, next for last() then second() then first()
	}, null) // null forces req,res to be bound to last() properly (w/o next)
}

var start = chainMiddleware([req, res], first, second, last);
start();