Reference to a function call

Kaptan Bhardwaj :

As we can assign a function call to a new reference in javascript for example we have a function display and when we call it we use display(). And we know in javascript we can also create a reference for this for example var call = display(),So can i invoke this function using this call() reference ? below is my code it is not working it is showing outerDisplay is not a function why is this happening ?

<script>
   var obj = {
       name: 'Saurabh',
       display: function () {
           console.log(this.name); // 'this' points to obj
       }
   };
   var outerDisplay = obj.display(); // Saurabh
   outerDisplay();
</script>

bravemaster :

outerDisplay is not a function because it already called obj.display(). However if you changed code like the below one, it won't work:

var outerDisplay = obj.display;
outerDisplay(); // it won't work!

Because it lost the "owner" of this function. You have to tell who is the owner with call.

var obj = {
    name: 'Saurabh',
    display: function(){
        console.log(this.name); // 'this' points to obj
    }
};
var outerDisplay=obj.display; // Saurabh
outerDisplay.call(obj); 

MDN web docs link: Function.prototype.call()