JavaScript Strings - JavaScript Tutorial

What is a String?

A string is a sequence of characters used to represent text. In JavaScript, strings are enclosed in single quotes ('), double quotes ("), or backticks (`).

// Example of Strings:

let singleQuote = 'Hello';
let doubleQuote = "World";
let templateLiteral = `Hello, World!`;
console.log(singleQuote);  // Output: Hello
console.log(doubleQuote);  // Output: World
console.log(templateLiteral);  // Output: Hello, World!

String Properties

Strings have properties that provide information about the string.

Length

The length property returns the number of characters in a string.

let text = "JavaScript";
console.log(text.length);  // Output: 10

String Methods

JavaScript provides various methods to manipulate strings.

1. charAt()

The charAt() method returns the character at a specified index.

let text = "JavaScript";
console.log(text.charAt(0));  // Output: J
console.log(text.charAt(4));  // Output: S

2. concat()

The concat() method concatenates two or more strings.

let text1 = "Hello";
let text2 = "World";
let result = text1.concat(", ", text2, "!");
console.log(result);  // Output: Hello, World!

3. includes()

The includes() method checks if a string contains a specified substring.

let text = "JavaScript is fun";
console.log(text.includes("fun"));  // Output: true
console.log(text.includes("boring"));  // Output: false

4. indexOf()

The indexOf() method returns the index of the first occurrence of a specified substring.

let text = "JavaScript";
console.log(text.indexOf("S"));  // Output: 4
console.log(text.indexOf("X"));  // Output: -1

5. replace()

The replace() method replaces a specified substring with another substring.

let text = "JavaScript is fun";
let newText = text.replace("fun", "awesome");
console.log(newText);  // Output: JavaScript is awesome

6. slice()

The slice() method extracts a part of a string and returns it as a new string.

let text = "JavaScript";
let part = text.slice(0, 4);
console.log(part);  // Output: Java

7. split()

The split() method splits a string into an array of substrings.

let text = "Hello, World!";
let words = text.split(" ");
console.log(words);  // Output: ["Hello,", "World!"]

8. substring()

The substring() method extracts characters from a string between two specified indices.

let text = "JavaScript";
let part = text.substring(4, 10);
console.log(part);  // Output: Script

9. toLowerCase() and toUpperCase()

The toLowerCase() method converts a string to lowercase, and the toUpperCase() method converts a string to uppercase.

let text = "JavaScript";
console.log(text.toLowerCase());  // Output: javascript
console.log(text.toUpperCase());  // Output: JAVASCRIPT

10. trim()

The trim() method removes whitespace from both ends of a string.

let text = "   JavaScript   ";
console.log(text.trim());  // Output: JavaScript

JavaScript Strings Example Code

Explanation of Code:

String Properties: Demonstrates the use of the length property.
String Methods: Demonstrates the use of various string methods such as charAt, concat, includes, indexOf, replace, slice, split, substring, toLowerCase, toUpperCase, and trim.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript Strings Example</title>
</head>
<body>
    <script>
        let text = "  JavaScript is fun!  ";

        // String properties
        console.log("Length: " + text.length);  // Output: Length: 20

        // String methods
        console.log("charAt(0): " + text.charAt(0));  // Output: charAt(0):  
        console.log("concat(): " + text.concat(" Let's learn it."));  // Output: concat():   JavaScript is fun!  Let's learn it.
        console.log("includes('fun'): " + text.includes("fun"));  // Output: includes('fun'): true
        console.log("indexOf('S'): " + text.indexOf("S"));  // Output: indexOf('S'): 5
        console.log("replace('fun', 'awesome'): " + text.replace("fun", "awesome"));  // Output: replace('fun', 'awesome'):   JavaScript is awesome!  
        console.log("slice(2, 12): " + text.slice(2, 12));  // Output: slice(2, 12): JavaScript
        console.log("split(' '): " + text.split(" "));  // Output: split(' '): ,JavaScript,is,fun!,,
        console.log("substring(2, 12): " + text.substring(2, 12));  // Output: substring(2, 12): JavaScript
        console.log("toLowerCase(): " + text.toLowerCase());  // Output: toLowerCase():   javascript is fun!  
        console.log("toUpperCase(): " + text.toUpperCase());  // Output: toUpperCase():   JAVASCRIPT IS FUN!  
        console.log("trim(): " + text.trim());  // Output: trim(): JavaScript is fun!
    </script>
</body>
</html>

What is a String?

String Properties

Length

String Methods

JavaScript Strings Example Code

JavaScript Labs