List of top Web Applications Questions on JavaScript asked in CBSE Class XII

In JavaScript, the value returned by Math.ceil(3.14) will be:

Write a JavaScript program that uses Math.random() to generate three random numbers greater than 10 and less than 100. The program should also display the sum of the numbers, the largest number, and the smallest number.
Note: Use built-in JavaScript functions wherever needed.

Predict the output of the following JavaScript code:
var colors = ['Red', 'Blue', 'Green'];
document.write(colors.pop() + "
");
document.write(colors.push('Yellow') + "
");
document.write(colors.join('& amp;') + "
");
document.write(colors.slice(1, 3));

What is the key difference between the JavaScript string methods replace() and replaceAll()? Support your answer with an example.

What are JavaScript event handlers? Explain the purpose of onmouseover.

Explain the purpose of the onload event handler in JavaScript.

Explain the purpose of the following JavaScript array methods:
(a) concat()
(b) reverse()

What is the role of the return keyword inside a JavaScript function ? Explain with an example.

What will be the output of the following JavaScript code ?
<html> <body> <script> document.write([21, 121, 120, 24, 202].sort()); </script> </body> </html>

Which of the following JavaScript statements can be used to access the last element of an array named myArray?

Which built-in JavaScript function is used to convert a value to an integer ?

Which array method in JavaScript is used to insert an element at the beginning of an array ?

Which of the following JavaScript event handlers is triggered when the mouse pointer leaves an HTML element?

What will be the output of the following JavaScript code?
<html> <body> <script> document.write(Math.pow(3,2)); </script> </body> </html>

Which JavaScript statement is used to delete the property age from the object person?

Which of the following is an invalid function name in JavaScript?

What will be the output of the following JavaScript code ?