bind

bindExample.js

function saySomething( message, name ) {
	console.log (message + " " + name + "!")
}

saySomething("Hi", "juanma") // "Hi juanma!"
saySomething("Bye", "juanma") // "Bye juanma!"

var sayHi = saySomething.bind(null, "Hi");
typeof sayHi === 'function' // true
sayHi("juanma")  // "Hi juanma!"

var sayBye = saySomething.bind(null, "Bye");
typeof sayBye === 'function' // true
sayBye("juanma")  // "Bye juanma!"

var sayHiToJuanma = saySomething.bind(null, "Hi", "juanma");
sayHiToJuanma()  // "Hi juanma!"