← Back to Roadmap

Data Types

Easy

In plain terms

JavaScript has 8 data types: string, number, bigint, boolean, undefined, null, symbol, and object. Use typeof to check types. Primitives are immutable; objects are passed by reference.

What you need to know

  • •Primitives: string, number, boolean, undefined, null, symbol, bigint
  • •Object: arrays, functions, plain objects
  • •typeof operator for type checking

Try it yourself

Copy the code below and run it in your browser console or a code editor:

typeof 'hello';    // "string"
typeof 42;        // "number"
typeof true;      // "boolean"
typeof undefined; // "undefined"
typeof null;      // "object" (historical bug)
typeof {};        // "object"
typeof [];        // "object"
typeof Symbol();  // "symbol"
typeof 10n;       // "bigint"

Learn more

Dive deeper with these trusted resources:

MDNjavascript.infoTutorialsPointW3Schools