this in global scope in Javascript - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this code in a browser?

Consider the following JavaScript code run in a browser environment. What will be logged to the console?

Javascript

console.log(this === window);

A true

B false

C undefined

D TypeError

💡 Hint

In browsers, the global object is 'window'.

In the global scope of a browser, 'this' refers to the global object, which is 'window'. So 'this === window' is true.

❓ Predict Output

intermediate

What does this log in Node.js global scope?

In Node.js, what will this code output when run as a script?

Javascript

console.log(this === global);

A false

B true

C undefined

D ReferenceError

💡 Hint

Node.js has a different global object than browsers.

In Node.js, the top-level 'this' in a module is not the global object. It is an empty object, so 'this === global' is false.

❓ Predict Output

advanced

What is the output of this strict mode code?

What will this code output when run in a browser console?

Javascript

"use strict";
console.log(this);

A Window object

B null

C undefined

D ReferenceError

💡 Hint

Strict mode changes the value of 'this' in the global scope.

In strict mode, 'this' in the global scope is undefined instead of the global object.

❓ Predict Output

advanced

What does this output inside a function in global scope?

What will this code output when run in a browser?

Javascript

function showThis() {
  console.log(this);
}
showThis();

A undefined

B Window object

C Function object

D ReferenceError

💡 Hint

In non-strict mode, 'this' inside a function called in global scope is the global object.

When a function is called normally in the global scope (non-strict mode), 'this' inside it refers to the global object (window in browsers).

❓ Predict Output

expert

What is the output of this arrow function in global scope?

What will this code output when run in a browser console?

Javascript

const arrowFunc = () => this;
console.log(arrowFunc() === window);

A false

B TypeError

C undefined

D true

💡 Hint

Arrow functions do not have their own 'this'.

Arrow functions inherit 'this' from their surrounding scope. In global scope, 'this' is the global object (window).