Variables in JavaScript do not have a “fixed type”.
Once you assign a value of some type to a variable, you can later reassign the variable to host a value of any other type, without any issue.
In JavaScript, we have 2 main kinds of types: primitive types and object types.
Primitive types are:
- numbers
- strings
- booleans
- symbols
And two special types: null and undefined.
Any value that’s not of a primitive type (a string, a number, a boolean, null, or undefined) is an object.
We’ll talk more about objects later on.
The main difference I mention now about primitive types and objects is that objects are passed by reference, while primitive types are passed by value. This is a concept that will be useful when we’ll introduce functions.