bind() method in JavaScript

bind() method - Hard binding

bind() method creates a new function that will have "this" set to the parameter passed to bind.

bind() method is used when we want "this" value to be predictable

	function displayName() {
	console.log(this.name);
	}
	var obj1 = {name: "Deepak"};
	var obj2 = {name: "Chetan"};
	var orig = displayName;
	var displayName = function() {
	orig.call(obj1);
	};
	displayName(); // "Deepak"
	displayName.call(obj2); // "Deepak"

view raw gistfile1.js hosted with ❤ by GitHub

In the above program displayName() method always has obj1 as "this" value.

	function bind2(fun, obj) {
	return function() {
	fun.call(obj);
	};
	}
	function displayName() {
	console.log(this.name);
	}
	var obj1 = {name: "Deepak"};
	var obj2 = {name: "Chetan"};
	var displayName = bind2(displayName, obj1);
	displayName(); // "Deepak"
	displayName.call(obj2); // "Deepak"

view raw gistfile1.js hosted with ❤ by GitHub

	if(!Function.prototype.bind2) {
	Function.prototype.bind2 = function(obj) {
	var fun = this;
	return function() {
	fun.apply(obj, arguments);
	};
	};
	}
	function displayName(lastName) {
	console.log(this.name + " " + lastName);
	}
	var obj1 = {name: "Deepak"};
	var obj2 = {name: "Chetan"};
	var displayName = displayName.bind2(obj1);
	displayName("Sisodiya"); // "Deepak Sisodiya"
	displayName.call(obj2, "Sisodiya"); // "Deepak Sisodiya"

view raw gistfile1.js hosted with ❤ by GitHub

	function displayName(lastName) {
	console.log(this.name + " " + lastName);
	}
	var obj1 = {name: "Deepak"};
	var obj2 = {name: "Chetan"};
	var displayName = displayName.bind(obj1);
	displayName("Sisodiya"); // "Deepak Sisodiya"
	displayName.call(obj2, "Sisodiya"); // "Deepak Sisodiya"

view raw gistfile1.js hosted with ❤ by GitHub

Link 1 - Hard binding
Link 2 - Hard binding
Link 3 - Hard binding
Link 4 - Hard binding