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Data Type in JavaScript

Data types are an essential concept in programming languages like JavaScript. They define the type of data that can be stored and manipulated in a program. Understanding data types is crucial for writing efficient and bug-free code. Let's explore the different data types in JavaScript:

1. Primitive Data Types:​

These are the basic building blocks of data.

String:​

  • A sequence of characters.
  • Defined with single (' ') or double (" ") quotes.
let greeting = "Hello, World!";

Number:​

  • Represents both integers and floating-point numbers.
  • No distinction between integers and floats.
let age = 25;
let price = 19.99;

Boolean:​

  • Represents either true or false.
let isStudent = true;

Undefined:​

  • Variable declared but not assigned.
let undefinedVar;

Null:​

  • Represents the intentional absence of any object value.
let nullVar = null;

Symbol (ES6 and later):​

  • Provides a unique value, often used as identifiers.
let id = Symbol('id');

2. Composite Data Types:​

These are used to store collections of data.

Array:​

  • Ordered list of values, accessed by index.
let colors = ['red', 'green', 'blue'];

Object:​

  • Unordered collection of key-value pairs.
let person = {
    name: 'John',
    age: 30,
    isStudent: false
};

3. Special Data Types:​

Function:​

  • A reusable block of code.
function addNumbers(a, b) {
    return a + b;
}

4. Type Coercion:​

  • JavaScript automatically converts one data type to another when needed.
let numString = "10";
let num = 5;

console.log(numString + num); // "105" (string concatenation)

5. Checking Data Types:​

  • Use typeof operator to check the data type of a variable.
let name = "John";
console.log(typeof name); // "string"

Understanding these data types is crucial for effective programming in JavaScript. They help you organize and manipulate data in your applications.