Strings in JavaScript

What is String?

A string in programming is a sequence of characters (letters, numbers, symbols, and spaces) typically used to represent text. Strings are often enclosed in quotation marks (" " or ' ').

String have some in build methods which can used in manipulation of string.

String Methods:-

Length Property

It is used to check the length of the string.

let fname = 'Priya'
console.log(fname.length); //5

CharAt()

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

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

concat()

The concat() method in JavaScript is used to join two or more strings together. It does not change the original strings but returns a new concatenated string.

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

Inculdes()

Checks if the string contains a substring (returns true or false).

//string.includes('str-elem', start-index)
let sentence = "The quick brown fox jumps over the lazy dog.";
onsole.log(sentence.includes("quick")); // true
console.log(sentence.includes("Quick")); // false
console.log(sentence.includes("lazy", 30)); // true

IndexOf()

Returns the index of the first occurrence of a substring.

let sentence = "The quick brown fox jumps over the lazy dog.";
console.log(sentence.indexOf("quick")); // 4

Slice(startIndex, endIndex)

Similar to substring() but supports negative indices to count from the end.

let sentence = "The quick brown fox jumps over the lazy dog.";
console.log(sentence.slice(4, 9)); // "quick"

Split(separator, liimit)

Splits the string into an array at the specified separator.

let sentence = "The quick brown fox jumps over the lazy dog.";
console.log(sentence.split(" "));

ToLowerCase()

Converts the string to lowercase.

let sentence = "The Quick Brown Fox.";
console.log(sentence.toLowerCase()); // "the quick brown fox."

ToUpperCase()

Converts the string to uppercase.

let sentence = "The Quick Brown Fox.";
console.log(sentence.toUpperCase()); // "THE QUICK BROWN FOX."

Trim()

Removes leading and trailing whitespace.

let greeting = "   Hello, World!   ";
console.log(greeting.trim()); // "Hello, World!"

Replace(searchValue, newValue)

Replaces occurrences of a substring with another substring.

let sentence = "The quick brown fox jumps over the lazy dog.";
console.log(sentence.replace("fox", "cat")); 
//The quick brown cat jumps over the lazy dog.

padStart() and padEnd()

It will give padding at start or at the end.

const originalString = "hello";
const paddedString = originalString.padStart(10, "Hey! "); //  // "-----hello"
const paddedString2 = originalString.padEnd(12, " Shweta"); // "hello-----"

Repeat()

Repeats the string count times.

const originalString = "hello";
const repeatedString = originalString.repeat(3); // "hellohellohello"
console.log(repeatedString);

StartsWith()

Checks if the string starts with the specified prefix (returns true or false).

const originalString = "hello world";
const startsWithHello = originalString.startsWith("hello"); // true

EndsWith()

Checks if the string ends with the specified suffix (returns true or false).

const originalString = "hello world";
const endsWithWorld = originalString.endsWith("world"); // true

CharCodeAt()

Returns the Unicode value of the character at the specified index.

let str = "Hello";
console.log(str.charCodeAt(1));  // 101 (Unicode for 'e')