What Do We Store in Boxes?

In JavaScript, a variable is not tied to a type forever. You can put a number in it, and later — a string. This is called dynamic typing.

1. Seven Primitive Types

1. Number: Integers and floats. Includes Infinity and NaN (Not-a-Number, e.g., result of "hello" / 2).
2. BigInt: For gigantically large numbers.
3. String: Text. Always in quotes. JS has no " char " type, only strings.
4. Boolean: Logical type. Only true or false.
5. Null: A special value that WE ASSIGN ourselves. Means " intentionally empty " .
6. Undefined: A value assigned by JS itself if a variable is created but has nothing in it.

2. New and Special

• BigInt: For huge numbers that don't fit into Number.
• Symbol: Unique identifiers.

3. Object (Complex Type)

Everything else in JS is an Object. It can store entire collections of data.

typeof 42; // "number"
typeof "Hello"; // "string"