An experiment to create named parameters in Javascript.

README.md

var createNamedParameters = require("./named-parameters")

var fn = createNamedParameters(["greeting", "person"], function(a, b) {
	console.log(a, b)
})

fn.greeting("hello") // set a
fn.person("world")   // set b
fn() // console.log gets run

// append additional parameters which were unnamed.
var extraParams = createNamedParameters(["world"], function(a, extra) {
	console.log(a, extra)
})

extraParams.world("first param") // set a
extraParams("extra param") // console.log gets run.

named-parameters.js

(function(global, factory) {
	// Defines a module that works in Node.js & Browsers
	var mock, local = (typeof module === "object" && module.exports) ? module :
		(mock = { exports: {} })
	factory(local, local.exports)
	if (local === mock) global["createNamedParameters"] = local.exports
}(this, function(module, exports) {
	module.exports = function createNamedParameters(argv, fn) {
		var i = 0
		var length = argv.length
		var composed = Array(length)

		function composing() {
			var i = 0, len = arguments.length
			composed.length = length + len
			for (; i < len; i++) composed[i] = arguments[i]

			try {
				return fn.apply(this, composed)
			} finally {
				composed = Array(length)
			}
		}

		for (; i < length; i++) addNamedParam(composing, composed, argv[i], i)

		return composing
	}

	// Check that we're not going to override a property of a function.
	function addNamedParam(fn, args, name, pos) {
		if (!name || name in fn)
			throw new ReferenceError("Can't use `" + name + "` as named parameter.")

		fn[name] = function curryParam(v) {
			args[pos] = v
			return fn
		}
	}
}))