String in DSA Using JavaScript (original) (raw)

Last Updated : 23 Jul, 2025

A string in JavaScript is a sequence of characters enclosed in single ('), double ("), or backticks (`). Strings in JavaScript are immutable, meaning their contents cannot be changed after creation. Any operation that modifies a string actually creates a new string.

**Example:

JavaScript `

let s = "GfG"; console.log(s[0]); console.log(s.length);

`

Common String Methods in JavaScript:

• length – Returns the number of characters in a string.
• charAt(index) – Returns the character at the specified index.
• slice(start, end) – Extracts a section of a string and returns it as a new string.
• substring(start, end) – Similar to slice(), but does not accept negative indices.
• toUpperCase() / toLowerCase() – Converts the string to uppercase or lowercase.
• trim() – Removes whitespace from both ends of a string.
• replace(searchValue, newValue) – Replaces a specified value with another value in a string.
• split(separator) – Splits a string into an array based on a specified separator.
• includes(substring) – Checks if a string contains a given substring, returning true or false.
• concat(str1, str2, ...) – Joins two or more strings together.
• Please refer JavaScript String Methods for more methods.

Easy Problems Problem On String using JavaScript

1. Reverse a String
2. Palindrome Check
3. Check for Subsequence
4. Check Anagram
5. Reverse Words
6. Isomorphic Strings
7. Check Pangram or not

Medium Problems On String in JavaScript

1. Implement Atoi
2. Validate an IP address
3. Find the largest word in dictionary
4. Equal 0, 1, and 2
5. Longest Palindromic Subsequence
6. Longest substring without Repeating

Hard Problems On String in JavaScript

1. Search Pattern (KMP-Algorithm)
2. Search Pattern (Rabin-Karp Algorithm)
3. Shortest Common Supersequence
4. Number of words with K maximum distinct vowels
5. Longest substring to form a Palindrome
6. Longest Valid Parenthesis