How to Create Hash From String in JavaScript?

To create a hash from a string in JavaScript, you can use hashing algorithms like MD5, SHA-1, or SHA-256. Here are the different methods to create HASH from string in JavaScript.

1. Using JavaScript charCodeAt() method

The JavaScript str.charCodeAt() method returns a Unicode character set code unit of the character present at the index in the string specified as the argument. The index number ranges from 0 to n-1, where n is the string’s length.

Syntax

str.charCodeAt(index)

function toHash(string) {  let hash = 0;  if (string.length == 0) return hash;  for (i = 0; i < string.length; i++) {  char = string.charCodeAt(i);  hash = ((hash << 5) - hash) + char;  hash = hash & hash;  }  return hash; } // String printing in hash let gfg = "GeeksforGeeks" console.log(toHash(gfg)); 

-1119635595 

2. Using crypto.createHash() method

The crypto.createHash() method in Node.js is used to create a hash object that can generate a hash of a given data using a specified algorithm, such as SHA-256, SHA-512, or MD5.

Syntax

const crypto = require('crypto'); const hash = crypto.createHash(algorithm);

• algorithm: A string representing the hashing algorithm to be used (e.g., 'sha256', 'sha512', 'md5').
• hash: The hash object that allows the hashing process to be updated with data and then generates the final hash.

const crypto = require('crypto'),  hash = crypto.getHashes(); x = "Geek" hashPwd = crypto.createHash('sha1')  .update(x).digest('hex'); console.log(hashPwd); 

321cca8846c784b6f2d6ba628f8502a5fb0683ae 

In this example

• Import crypto module: Allows access to cryptographic functions.
• Define input string: Sets the string to be hashed.
• Create SHA-1 hash: Creates a SHA-1 hash and converts the input string into its hex representation.
• Log the hash: Prints the resulting hash of "Geek" to the console.

3. Using JavaScript String's reduce() Method

The reduce() method in JavaScript is typically used with arrays to reduce them to a single value. It can also be used with strings to create custom operations, like generating a simple hash from a string.

function toHash(string) {  return string.split('').reduce((hash, char) => {  return char.charCodeAt(0) + (hash << 6) + (hash << 16) - hash;  }, 0); } let gfg = "GeeksforGeeks"; console.log(toHash(gfg)); 

-2465134923 

In this example:

• split(''): This converts the string into an array of characters.
• reduce(): The reduce() method loops through the array, performing a cumulative operation on each character. The operation here is to add the character's ASCII value to an accumulator.
• char.charCodeAt(0): This gets the ASCII code of each character.
• Accumulator (acc): This starts at 0 and keeps adding the ASCII values of each character.

4. Using SHA-256 algorithm

The crypto module in Node.js allows developers to work with cryptographic operations like hashing. The createHash() method is commonly used to create a hash of a given input using algorithms like SHA-256.

const crypto = require('crypto'); function createSHA256Hash(inputString) {  const hash = crypto.createHash('sha256');  hash.update(inputString);  return hash.digest('hex'); } // Example usage const inputString = "Hello, World!"; const hashValue = createSHA256Hash(inputString); console.log(hashValue); 

Output

2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

5. Using the crypto.subtle API (Browser Environment)

The crypto.subtle API is built into modern browsers and provides a way to perform cryptographic operations like hashing. Here is how you can generate a SHA-256 hash in the browser using crypto.subtle

async function hashString(inputString) {  const encoder = new TextEncoder();  const data = encoder.encode(inputString);   const hashBuffer = await crypto.subtle.digest('SHA-256', data);   const hashArray = Array.from(new Uint8Array(hashBuffer));   const hashHex = hashArray.map(byte => byte.toString(16).padStart(2, '0')).join('');   return hashHex; } hashString("Hello, World!").then(hash => {  console.log("Hash: " + hash); }); 

Output

Hash: a591a6d40bf420404a011733cfb7b190d62c65bf0bcda7c8a660e3a1b3cfbf1b 

In this example

• The TextEncoder converts the string into a byte array.
• The crypto.subtle.digest() method performs the SHA-256 hashing.
• The result is a ArrayBuffer, which we convert to an array of bytes and then to a hexadecimal string.