Skip to content

How can you tell what type a value is, in JavaScript?

New Course Coming Soon:

Get Really Good at Git

JavaScript has a few built-in types, including numbers, strings, booleans, objects.

Using the typeof operator we can check what is the type of a value assigned to a variable.

For example:

typeof 'test'

Note that it’s not a function, it’s an operator, so parentheses are not required.

Using it, we will get a string back, returning one of the following values:

Note that there is no null type, and

typeof null

will return 'object'.

Arrays will return 'object' too:

typeof [1, 2, 3] //'object'

Functions are a special kind of objects, as we can add properties and methods to functions:

const talk = () => {}
talk.test = true

but they have their own value 'function' if we use the typeof operator.

Are you intimidated by Git? Can’t figure out merge vs rebase? Are you afraid of screwing up something any time you have to do something in Git? Do you rely on ChatGPT or random people’s answer on StackOverflow to fix your problems? Your coworkers are tired of explaining Git to you all the time? Git is something we all need to use, but few of us really master it. I created this course to improve your Git (and GitHub) knowledge at a radical level. A course that helps you feel less frustrated with Git. Launching May 21, 2024. Join the waiting list!
→ Get my JavaScript Beginner's Handbook
→ Read my JavaScript Tutorials on The Valley of Code
→ Read my TypeScript Tutorial on The Valley of Code

Here is how can I help you: