JavaScript Variables and Data Types

What is the purpose of variables in JavaScript?

• Variables in JavaScript are unnecessary and should be avoided.

• Variables in JavaScript are used to confuse programmers.

• The purpose of variables in JavaScript is to make the code more complicated.

• The purpose of variables in JavaScript is to store and manipulate data.

Which keyword is used to declare a variable in JavaScript?

• function

• var

• const

• let

What are the different data types supported by JavaScript?

• integer, float, array, function, character, boolean, object

• text, decimal, list, method, character, true, false

• word, digit, list, function, character, true, false

• string, number, boolean, null, undefined, object, symbol

How do you declare a string variable in JavaScript?

• var myString = 'Hello';

• let myString = 'Hello';

• const myString = 'Hello';

• var myString = 'Hello World';

What is the difference between null and undefined in JavaScript?

• null is a value that is automatically assigned to variables that have not been assigned a value, while undefined represents intentional absence of any object value

• null is used to represent a value that is unknown or has not been set, while undefined is used to represent a variable that has been declared but has not been assigned a value

• null is a value that is automatically assigned to variables that have not been assigned a value, while undefined is used to represent a value that is unknown or has not been set

• null represents intentional absence of any object value, while undefined is automatically assigned to variables that have not been assigned a value

How do you declare a number variable in JavaScript?

• let num = 10;

• var num = '10';

• var num = 10;

• const num = 10;

What is the result of adding a number and a string in JavaScript?

• The result is an error.

• The result is a number.

• The result is a boolean.

• The result is a string concatenation.

What is the purpose of the typeof operator in JavaScript?

• The typeof operator in JavaScript is used to compare two variables or expressions.

• The typeof operator in JavaScript is used to convert a variable or expression to a string.

• The typeof operator in JavaScript is used to perform mathematical operations on variables or expressions.

• The purpose of the typeof operator in JavaScript is to determine the type of a variable or expression.

How do you declare a boolean variable in JavaScript?

• var isTrue = 'true';

• var isTrue = true;

• var isTrue = 1;

• var isTrue = false;

What is the value of NaN in JavaScript?

• Number

• Not a Number

• Undefined

• Null