Javascript: call vs bind vs apply

 Hello Everyone, 

I came across a snippet where code have .call() method.

Thought its been a while since I went through their understanding, via this article I am explaining with examples what call, bind and apply does in javascript.

Please read comments for understanding.

Hope it helps.

var obj = {

name: "Raja",

sayHello: function(args) {

console.log(`Hello ${this.name}, How are you doing `);

},

};

// call : Changing the context::this scope to the argument we are passing.

// normal

obj.sayHello() // Hello Raja, How are you doing ?

obj.sayHello.call({name : "Rajasekhar"}); // Hello Rajasekhar, How are you doing ?

var obj = {

name: "Raja",

sayHello: function(args) {

console.log(`Hello ${this.name}, How are you doing ? ${args}`);

},

};

// apply: same as call, we can also pass arguments as 2nd argument

obj.sayHello.apply({ name: "Rajasekhar" }, ["Testing"]); // Hello Rajasekhar, How are you doing ? Testing

// bind: Change function definition to a different context

// you can change the definition once

var obj = {

name: "Raja",

sayHello: function(args) {

console.log(`Hello ${this.name}, How are you doing ? ${args}`);

},

};

var contxt = {"name" : "ApplyContext:)"};

var newHello = obj.sayHello.bind(contxt);

newHello("Good Day!!!"); // Hello ApplyContext:), How are you doing ? Good Day!!!