Data types in javascript
JavaScript has several built-in data types that can be categorized into two main groups: primitive types and object types.
### Primitive Data Types
These are the most basic types of data in JavaScript, and they are immutable (i.e., their values cannot be changed). The primitive data types are:
1. **Number**: Represents both integer and floating-point numbers. Example: `42`, `3.14`
- JavaScript uses a double-precision 64-bit binary format (IEEE 754) for all numbers.
2. **String**: A sequence of characters used for text. Strings are enclosed in single quotes (`'`), double quotes (`"`), or backticks (`` ` ``). Example: `'Hello, World!'`, `"JavaScript"`, `` `Template String` ``
3. **Boolean**: Represents a logical entity that can be either `true` or `false`. Example: `true`, `false`
4. **Undefined**: A variable that has been declared but has not yet been assigned a value. Example:
```javascript
let x;
console.log(x); // Output: undefined
```
5. **Null**: Represents the intentional absence of any object value. It is a primitive value that represents "nothing." Example: `let y = null;`
6. **Symbol**: Introduced in ES6 (ECMAScript 2015), symbols are unique and immutable data types often used as object property keys. Example:
```javascript
const sym = Symbol('description');
```
7. **BigInt**: A numeric data type that can represent integers with arbitrary precision. BigInt is used for very large numbers that cannot be represented by the `Number` type. Example:
```javascript
const bigIntValue = BigInt(1234567890123456789012345678901234567890);
```
### Object Data Type
In addition to primitive types, JavaScript has a special data type called an Object, which is used to store collections of data and more complex entities.
- **Object**: Objects are collections of key-value pairs and can hold any type of data, including other objects. They are mutable. Example:
```javascript
const person = {
name: 'Alice',
age: 25,
isStudent: false
};
```
JavaScript also has some built-in object types:
- **Array**: A special type of object used to store ordered collections of values. Arrays can hold any type of data. Example:
```javascript
const numbers = [1, 2, 3, 4, 5];
```
- **Function**: Functions are also treated as objects in JavaScript. They can be stored in variables, passed as arguments to other functions, and returned from functions. Example:
```javascript
function greet() {
console.log('Hello!');
}
```
- **Date**: Used for handling date and time. Example:
```javascript
const now = new Date();
```
- **RegExp**: Regular expressions for pattern matching in strings. Example:
```javascript
const regex = /abc/;
```
### Summary
- **Primitive data types**: Number, String, Boolean, Undefined, Null, Symbol, BigInt
- **Object data type**: Objects (including Arrays, Functions, Dates, and Regular Expressions)
Understanding these data types is fundamental for programming in JavaScript, as they define how data can be manipulated and interacted with in your code.