why "this" keyword returns undefined always in node.js?

Asked Nov 11 '19 at 19:05

Active Nov 11 '19 at 19:11

Viewed 147 times

Everyone I'm beginner in JS.I read articles.As per my knowledge "this" keyword is a global object.If we use "strict" then it will be undefined..why I'm getting different output in javascript browser and Node.js version.could anyone explain me please?

scenario1:

(Javascript Browser):

var count=5;

console.log(count);  //5

console.log(this.count); //5


(Node.JS 12.13.0)

var count=5;

console.log(count);  //5

console.log(this.count); //undefined


scenario2:

(Javascript Browser):

function ghost() {
  console.log(this.boo);
}

ghost(); // ABC

var boo = 'ABC';

ghost(); //ABC

(Node.JS 12.13.0)

function ghost() {
  console.log(this.boo);
}

ghost(); // undefined

var boo = 'ABC';

ghost(); //undefined

asked Nov 11 '19 at 19:05

vigneshRavi

`this` is _never_ `undefined` in any of the cases you’ve presented. Accessing a _property_ of it resolves to `undefined`. – Sebastian Simon Nov 11 '19 at 19:11
`this` is not an object, it's a reference to the object it belongs and the object could be the windows or any other object. – Addis Nov 11 '19 at 19:13
Also, the output of your scenario 2 is wrong: the first `ghost();` logs `undefined`. – Sebastian Simon Nov 11 '19 at 19:13
Are you saying undefined for Node.JS or JS in scenario2? – vigneshRavi Nov 11 '19 at 19:21
@vigneshRavi The first `ghost();` for both environments. – Sebastian Simon Nov 11 '19 at 19:25
See [Using 'var' and 'this' in the global scope in node.js program](https://stackoverflow.com/q/32370806/4642212). – Sebastian Simon Nov 11 '19 at 19:25

why "this" keyword returns undefined always in node.js?

0 Answers0