JavaScript Strings

In JavaScript, a string is a sequence of characters enclosed in single or double quotes. Strings can be manipulated using various string methods available in JavaScript.

Declaring a string in JavaScript

To declare a string variable in JavaScript, use the following syntax

let stringVariable = 'Hello, World!';

This declares a string variable named stringVariable and assigns the value 'Hello, World!' to it.

String methods

There are many built-in string methods in JavaScript. Here are some commonly used ones:

1. length: returns the length of the string

let str = 'Hello, World!';
console.log(str.length); // Outputs: 13

2. toUpperCase(): converts the string to uppercase

let str = 'Hello, World!';
console.log(str.toUpperCase()); // Outputs: HELLO, WORLD!

3. toLowerCase(): converts the string to lowercase

let str = 'Hello, World!';
console.log(str.toLowerCase()); // Outputs: hello, world!

4.indexOf(): returns the index of the first occurrence of a specified substring

let str = 'Hello, World!';
console.log(str.indexOf('o')); // Outputs: 4

5. substring(): returns a substring of the string

let str = 'Hello, World!';
console.log(str.substring(0, 5)); // Outputs: Hello

6. replace(): replaces a specified substring with another string

let str = 'Hello, World!';
console.log(str.replace('World', 'Universe')); // Outputs: Hello, Universe!

Concatenating strings

You can concatenate strings in JavaScript using the + operator or the concat() method. Here’s an example using the + operator:

let firstName = 'John';
let lastName = 'Doe';
console.log(firstName + ' ' + lastName); // Outputs: John Doe

String interpolation

String interpolation allows you to embed expressions inside a string literal. In JavaScript, you can use template literals (enclosed in backticks) for string interpolation. Here’s an example:

let firstName = 'John';
let lastName = 'Doe';
console.log(`My name is ${firstName} ${lastName}.`); // Outputs: My name is John Doe.

Strings are a fundamental data type in JavaScript, and manipulating strings is a common task in web development. Understanding string methods and concatenation techniques is important for working with strings effectively in JavaScript.