Data Types

There are 8 basic data types in JavaScript.

• Seven primitive data types:
  • number for numbers of any kind: integer or floating-point, integers are limited by ±(2^53 - 1).
  • bigint for integer numbers of arbitrary length.
  • string for strings. A string may have zero or more characters, there’s no separate single-character type.
  • boolean for true/false.
  • null for unknown values – a standalone type that has a single value null.
  • undefined for unassigned values – a standalone type that has a single value undefined.
  • symbol for unique identifiers.
• And one non-primitive data type:
  • object for more complex data structures.

The typeof operator allows us to see which type is stored in a variable.

• Usually used as typeof x, but typeof(x) is also possible.
• Returns a string with the name of the type, like "string".
• For null returns "object" – this is an error in the language, it’s not actually an object.