Common JavaScript Interview Question: What are some data types in JavaScript?

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There are 8 basic data types in JavaScript.

1. Null
2. Undefined
3. Number
4. Boolean
5. BigInts
6. Object
7. String
8. Symbol

How to remember them? Learn the mnemonic: NUNBBOSS.

Now that we know there are 8 data types, what exactly are these data types used for?

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Of the 8 data types, 7 are primitive. And what exactly does “primitive” mean?

A primitive data type can contain only a single thing. All primitive types are immutable and we cannot set properties on them.

Objects are the only non-primitive type because they are used to store collections of data and more complex entities.

You might be thinking, “Hey but I heard that everything in JavaScript is an object! If a string is not an object, how come I can do the following:

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The above logic makes the string “hi” look like an object because we are using a method on it. This is an illusion! JavaScript will create a temporary object when we want to use a method for a primitive type and then immediately discard it!