[Solved] Please explain the behavior in the below picture

by


This is due to the behavior of the “this” keyword on the different contexts where it’s been used.

So here is the complete reference for this keyword

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this

var foo = {  
    bar : function(){ 
            console.log(this); // For your reference
            return this.baz;  
          },
    baz: 1
};

(function(v){
    console.log(typeof arguments[0]()); // In this context "this" keyword refers to the current function "bar" and not the parent foo object, As the current function doesn't contain baz it returns undefined
    console.log(typeof foo.bar());  // In this context "this" keyword refers to its parent "foo" Object so this.baz will be refer to foo.baz and typeof 1 is a number
    console.log(typeof v()); // Here "this" keyword refers to the window object hence this.baz will refer to window.baz which is undefined
    return typeof arguments[0]();
})(foo.bar);

solved Please explain the behavior in the below picture