String Methods In Js

String Methods
JavaScript provides a variety of built-in methods to manipulate and work with strings. These methods make it easier to perform operations like searching, slicing, replacing, and transforming strings. Strings are immutable, so these methods return a new string or value without modifying the original string.

Here are some of the most commonly used string methods in JavaScript:

1. Accessing Characters

charAt(index): Returns the character at a specific index.

charCodeAt(index): Returns the Unicode value of the character at a specific index.

let str = "Hello, World!";
console.log(str.charAt(0)); // "H"
console.log(str.charCodeAt(0)); // 72 (Unicode of 'H')

2. Searching Strings

indexOf(value):

Returns the first index of the specified value, or -1 if not found.

lastIndexOf(value):

Returns the last index of the specified value.

includes(value):

Checks if a string contains a specified value; returns true or false.

startsWith(value):

Checks if a string starts with a specific value. endsWith(value): Checks if a string ends with a specific value.

let str = "Hello, JavaScript!";
console.log(str.indexOf("Java")); // 7
console.log(str.lastIndexOf("o")); // 4
console.log(str.includes("Script")); // true
console.log(str.startsWith("Hello")); // true
console.log(str.endsWith("!")); // true

3. Extracting Parts of Strings

slice(start, end): Extracts a portion of a string and returns it.

substring(start, end): Similar to slice, but cannot accept negative indexes.

substr(start, length): Extracts a substring based on the starting index and length. (Deprecated but still supported)

let str = "JavaScript is fun!";
  console.log(str.slice(0, 10)); // "JavaScript"
  console.log(str.substring(4, 10)); // "Script"
  console.log(str.substr(0, 4)); // "Java"

4. Modifying Strings

toUpperCase(): Converts the string to uppercase.

toLowerCase(): Converts the string to lowercase.

trim(): Removes whitespace from both ends of a string.

trimStart() / trimEnd(): Removes whitespace from the start or end of a string.

let str = "  Hello World!  ";
console.log(str.toUpperCase()); // "  HELLO WORLD!  "
console.log(str.toLowerCase()); // "  hello world!  "
console.log(str.trim()); // "Hello World!"
console.log(str.trimStart()); // "Hello World!  "
console.log(str.trimEnd()); // "  Hello World!"

5. Replacing Content

replace(value, newValue): Replaces the first occurrence of a value.

replaceAll(value, newValue): Replaces all occurrences of a value.

let str = "I love JavaScript. JavaScript is amazing!";
console.log(str.replace("JavaScript", "JS")); // "I love JS. JavaScript is amazing!"
console.log(str.replaceAll("JavaScript", "JS")); // "I love JS. JS is amazing!"

6. Splitting and Joining Strings

split(delimiter): Splits the string into an array based on a delimiter.

concat(value1, value2, ...): Concatenates two or more strings.