JavaScript Basics for Beginners

Test your understanding of variables,functions,and loops in JS.

1. Which keyword is used to declare a block-scoped variable in JavaScript?

var let const function

2. Which of the following are primitive data types in JavaScript? (Select all that apply)

String Number Boolean Object Null Array

3. JavaScript is a statically typed programming language.

True False

4. What is the output of console.log(2 + '2')?

5. What is the result of the expression: 5 > 3 && 2 > 7?

true false undefined NaN

6. Which array method adds an element to the end of an array?

push() pop() shift() unshift()

7. What does the acronym 'NaN' stand for in JavaScript?

Not a Number Null and Number New Array Notation None of the above

8. Which loop is used to iterate over the properties of an object?

for for...in for...of while

9. What is the output of typeof null?

null object undefined number

10. Which function converts a string to an integer?

parseInt() parseFloat() toInt() stringToInt()

11. Which of the following are valid JavaScript variable names? (Select all that apply)

myVar 1var var-1 _var $var

12. Which array methods modify the original array? (Select all that apply)

push() slice() splice() map() reverse()

13. Which of the following are comparison operators in JavaScript? (Select all that apply)

== === = != !==

14. Which of the following are ways to create a function in JavaScript? (Select all that apply)

Function declaration Function expression Arrow function Object constructor Class constructor

15. The 'this' keyword in a global function refers to the window object in web browsers.

True False

16. An empty array ([]) is considered falsy in JavaScript.

True False

17. JavaScript code always executes line by line from top to bottom without exceptions.

True False

18. What keyword is used to exit a loop early?

19. What is the output of console.log(typeof 'Hello World')?

20. What does the acronym JSON stand for?

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