Consider the JavaScript Code :

var y= ’’12”;

function f( ) {

var y=’’6”;

alert (this.y);

function g( ) {alert (y); }

g( );

}

f( );

If M is the number of alert dialog boxes generated by this JavaScript code and D1, D2, ....,

D_M represents the content displayed in each of the M dialog boxes, then :

Concept:

In Javascript, this keyword holds the reference to an object. It may be different each time the function is called. In global execution context (outside of a function), “this” refers to the global object whether in strict mode or not. Inside a function, value of “this” keyword depends on how function is called.

Explanation:

Given code :

var y= ’’12”;

function f( ) {

var y=’’6”;

alert (this.y);

function g( ) {alert (y); }

g( );

}

f( );

In this Javascript code, alert box appear two times. So value of m becomes .

First alert box will show the value of y as 12, as it takes the global value which is outside from the function. So, d₁ becomes 12.

Second alert box show the value of y as 6. It takes the local value which is inside the function. So, d₂ becomes 6.