JavaScript String Methods

JavaScript provides a variety of methods to work with strings. Here are some commonly used string methods:

1. length

The length property returns the length of a string:

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

2. charAt()

The charAt() method returns the character at a specified index (position) in a string:

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

3. concat()

The concat() method joins two or more strings:

  
    var str1 = "Hello, ";
    var str2 = "world!";
    console.log(str1.concat(str2)); // Output: Hello, world!

4. indexOf()

The indexOf() method returns the index of the first occurrence of a specified value in a string:

  
    var str = "Hello, world!";
    console.log(str.indexOf("world")); // Output: 7

5. lastIndexOf()

The lastIndexOf() method returns the index of the last occurrence of a specified value in a string:

  
    var str = "Hello, world! Hello, world!";
    console.log(str.lastIndexOf("world")); // Output: 19

6. slice()

The slice() method extracts a section of a string and returns it as a new string:

  
    var str = "Hello, world!";
    console.log(str.slice(7)); // Output: world!

7. substring()

The substring() method extracts the characters from a string, between two specified indices, and returns the new sub-string:

  
    var str = "Hello, world!";
    console.log(str.substring(7, 12)); // Output: world

8. substr()

The substr() method extracts parts of a string, beginning at the character at the specified position, and returns the specified number of characters:

  
    var str = "Hello, world!";
    console.log(str.substr(7, 5)); // Output: world

9. replace()

The replace() method searches a string for a specified value, or a regular expression, and returns a new string where the specified values are replaced:

  
    var str = "Visit Microsoft!";
    var newStr = str.replace("Microsoft", "Google");
    console.log(newStr); // Output: Visit Google!

10. split()

The split() method splits a string into an array of substrings based on a specified separator:

  
    var str = "Hello, world!";
    console.log(str.split(", ")); // Output: ["Hello", "world!"]

11. toUpperCase() / toLowerCase()

The toUpperCase() method converts a string to uppercase, while the toLowerCase() method converts a string to lowercase:

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

12. trim()

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

  
    var str = "   Hello, world!   ";
    console.log(str.trim()); // Output: Hello, world!

13. startsWith()

The startsWith() method determines whether a string begins with the characters of a specified string:

  
    var str = "Hello, world!";
    console.log(str.startsWith("Hello")); // Output: true

14. endsWith()

The endsWith() method determines whether a string ends with the characters of a specified string:

  
    var str = "Hello, world!";
    console.log(str.endsWith("world!")); // Output: true

15. includes()

The includes() method determines whether a string contains the specified characters:

  
    var str = "Hello, world!";
    console.log(str.includes("world")); // Output: true