JavaScript Data Types

Data Types

Data types are an important concept of any programming language. JavaScript supports a number of different data types, including strings, numbers, arrays, objects, and booleans. Understanding how to use each of these data types is essential to writing effective JavaScript code.

A string is a sequence of characters, such as "hello world". Strings can be single-quoted, double-quoted, or back-tick quoted. Strings can be concatenated, or combined, with the + operator.

// Concatenating strings
let str1 = 'Hello';
let str2 = 'World';
let str3 = str1 + ' ' + str2;

console.log(str3); // 'Hello World'

A number is a numerical value, such as 3, -5, or 0.5. Numbers can be used in mathematical operations, such as addition (+), subtraction (-), multiplication (*), and division (/).

// Basic math
let x = 3;
let y = 5;
let z = x + y;

console.log(z); // 8

An array is a collection of values, such as [1, 2, 3]. Arrays can contain any type of data, including strings and objects. Arrays are indexed, which means that each element in the array can be accessed using its index, or position in the array.

// Accessing array elements
let arr = [1, 2, 3];
let firstElement = arr[0];

console.log(firstElement); // 1

An object is a collection of key-value pairs, such as {name: 'John', age: 30}. Objects are used to store data in a structured way. Keys are strings, and values can be any type of data.

// Accessing object properties
let obj = {name: 'John', age: 30};
let name = obj.name;

console.log(name); // 'John'

A boolean is a value that can be either true or false. Booleans are used to represent the state of a variable or expression. For example, a variable can be set to true if a condition is met, and false if the condition is not met.

// Boolean values
let isValid = true;

if (isValid) {
  console.log('Valid!');
}