JavaScript Basics

Question 1

What is the data type that is missing: string, number, boolean, null…

Answer 1

undefined

Question 2

What is the instruction to display something in the console?

Answer 2

console.log

Question 3

How do you comment a single line?

Answer 3

//

Question 4

Instruction to display a message in a pop up window

Answer 4

alert

Question 5

Instruction to display the kind of variable

Answer 5

typeof

Question 6

What is the data type that is missing: string, number, boolean, undefined…

Answer 6

null

Question 7

How to comment multiple lines?

Answer 7

/**/

Question 8

Instruction to display a field in a pop up window?

Answer 8

prompt

Question 9

What is the sign used to check if a variable is equal to something?

Answer 9

===

Question 10

How do you code AND?

Answer 10

&&

Question 11

How do you code OR?

Answer 11

||

Question 12

If you are older than 18 you can drink beer, if not you can drink juice. How do you code this using the 2 following variables: beverage and age?

Answer 12

var beverage = age > 18 ? ‘beer’ : ‘juice’;

Question 13

What is used in a switch statement?

Answer 13

case and break

Question 14

What would you use in a switch statement to assign a value that is not assigned by “case”?

Answer 14

default

Question 15

What would you use if you want to use an equality operator with a string and a number?

Answer 15

==

Question 16

What should replace XXXXX if you want to use the result later?

function calculateAge(birthYear) {
    XXXXX 2018 - birthYear;
}

Answer 16

return

Question 17

What does DRY mean?

Answer 17

Don’t repeat yourself