JavaScript Basic Programs for Beginners

1.		Which of the following is NOT a valid way to comment in JavaScript?

// This is a comment

/* This is a comment /

# This is a comment

2.		Which of the following is NOT a valid JavaScript data type?

number

string

array

tuple

3.

What is the output of the following program?

console.log(typeof "hello");

number

string

boolean

undefined

4.

What is the output of the following code snippet?

console.log("hello".indexOf("l"));

1

2

3

4

5.

What is the output of the following code snippet?

console.log("hello".length);

hello

5

null

undefined

6.

What is the output of the following code snippet?

console.log(3 === "3");

1

0

null

undefined

7.

What is the output of the following program?

console.log("hello".toUpperCase());

HELLO

hello

hElLo

null

8.		Which of the following is the correct way to check if a variable is an array in JavaScript?

if (typeof myArray === "array") {}

if (myArray.isArray()) {}

if (myArray === "Array") {}

if (Array.isPrototypeOf(myArray)) {}

9.		Which of the following is the correct way to add an element to the end of an array in JavaScript?

myArray.push(newElement);

myArray.add(newElement);

myArray.insert(newElement, myArray.length);

myArray[myArray.length] = newElement;

10.		Which of the following is the correct way to create an array in JavaScript?

var myArray = ();

var myArray = [];

myArray = array();

myArray = {};