JavaScript String

The JavaScript String is a sequence of characters that is used to represent text. You can create a String using single quotes, double quotes, or backticks. Here are some examples:

let myString1 = 'Hello, world!';
let myString2 = "This is a string.";
let myString3 = `Another string.`;

The String object provides many methods for working with strings. Here are some of the most commonly used ones:

• length: Returns the number of characters in a string.
• charAt(index): Returns the character at the specified index in a string.
• concat(str1, str2, ...): Combines two or more strings and returns the result.
• indexOf(searchValue, fromIndex): Returns the index of the first occurrence of a specified value in a string, starting from a specified index. Returns -1 if the value is not found.
• lastIndexOf(searchValue, fromIndex): Returns the index of the last occurrence of a specified value in a string, starting from a specified index. Returns -1 if the value is not found.
• slice(startIndex, endIndex): Extracts a section of a string and returns it as a new string.
• substring(startIndex, endIndex): Similar to slice(), but does not accept negative indices.
• toLowerCase(): Converts a string to lowercase.
• toUpperCase(): Converts a string to uppercase.
• trim(): Removes whitespace from both ends of a string.
• split(separator): Splits a string into an array of substrings based on a specified separator.

Here are some examples of using these methods:

let myString = 'Hello, world!';

console.log(myString.length); // Output: 13

console.log(myString.charAt(1)); // Output: "e"

let newString = myString.concat(' This is an additional text.');

console.log(newString); // Output: "Hello, world! This is an additional text."

console.log(myString.indexOf('o')); // Output: 4

console.log(myString.lastIndexOf('o')); // Output: 8

console.log(myString.slice(0, 5)); // Output: "Hello"

console.log(myString.substring(7, 12)); // Output: "world"

console.log(myString.toLowerCase()); // Output: "hello, world!"

console.log(myString.toUpperCase()); // Output: "HELLO, WORLD!"

let myStringWithSpaces = ' Hello, world! ';
console.log(myStringWithSpaces.trim()); // Output: "Hello, world!"

let myStringWithCommas = 'apple,orange,banana';
console.log(myStringWithCommas.split(',')); // Output: ["apple", "orange", "banana"]