Data Types in JavaScript

JavaScript has two main data types: primitives and objects. Let's examine each of them.

Primitive Types

Primitives are basic data types. Their value is immutable, and they're passed by value.

List of Primitives

Objects

Objects are collections of data and functionality. They're passed by reference.

Examples of Objects

• Object — basic object.
• Array — ordered data collection.
• Function — object representing executable code.
• Date — object for working with dates.
• RegExp — object for working with regular expressions.

Examples of Creating Objects

// Regular object
const obj = { name: "John", age: 30 };

// Array
const arr = [1, 2, 3];

// Function
function greet() {
  console.log("Hello!");
}

typeof Examples

// typeof examples
console.log(typeof obj); // "object"
console.log(typeof arr); // "object"
console.log(typeof greet); // "function"
console.log(typeof null); // "object" (JS peculiarity)
console.log(typeof undefined); // "undefined"
console.log(typeof 42); // "number"
console.log(typeof "Hello"); // "string"
console.log(typeof Symbol("id")); // "symbol"
console.log(typeof 123n); // "bigint"