How to Use String Functions in JavaScript?

JavaScript provides several built-in string functions for manipulating strings. Here are a few of the most commonly used string functions:

1. length: Returns the length of a string.

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

2. concat: Joins two or more strings and returns a new string.

let str1 = "Hello, ";
let str2 = "World!";
let str3 = str1.concat(str2);
console.log(str3); // Output: "Hello, World!"

3. charAt: Returns the character at a specified index in a string.

let str = "Hello, World!";
console.log(str.charAt(0)); // Output: "H"

4. indexOf: Returns the first index at which a given element can be found in the string, or -1 if it is not present.

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

5. slice: Extracts a section of a string and returns a new string.

let str = "Hello, World!";
console.log(str.slice(7, 13)); // Output: "World"

6. replace: Replaces the first match of a string or a regular expression with a replacement string.

let str = "Hello, World!";
console.log(str.replace("World", "Friend")); // Output: "Hello, Friend!"

7. toUpperCase and toLowerCase: Converts a string to all upper case or all lower case letters.

let str = "Hello, World!";
console.log(str.toUpperCase()); // Output: "HELLO, WORLD!"
console.log(str.toLowerCase()); // Output: "hello, world!"

These are just a few of the most commonly used string functions in JavaScript. You can find more information on the available string functions in the JavaScript documentation.