How to create hash from string in JavaScript ?
To create a unique hash from a specific string, it can be implemented using its own string-to-hash converting function. It will return the hash equivalent of a string. Also, a library named Crypto can be used to generate various types of hashes like SHA1, MD5, SHA256, and many more.
These are the following methods to Create Hash from String:
Table of Content
Note: The hash value of an empty string is always zero.
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)Example: In this example, we will create a hash from a string in Javascript.
function stringToHash(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(stringToHash(gfg));
Output
-1119635595
Using crypto.createHash() method
The crypto.createHash() method is used to create a Hash object that can be used to create hash digests by using the stated algorithm.
Syntax:
crypto.createHash( algorithm, options )Example: In this example, we will create a hash from a string in Javascript.
// Importing 'crypto' module
const crypto = require('crypto'),
// Returns the names of
// supported hash algorithms
// such as SHA1,MD5
hash = crypto.getHashes();
// Create hash of SHA1 type
x = "Geek"
// 'digest' is the output
// of hash function containing
// only hexadecimal digits
hashPwd = crypto.createHash('sha1')
.update(x).digest('hex');
console.log(hashPwd);
Output
321cca8846c784b6f2d6ba628f8502a5fb0683ae
Using JavaScript String’s reduce() Method
The reduce() method in JavaScript applies a function to each element of the array (or in this case, each character of the string) to reduce the array to a single value. In this method, we can accumulate a hash value by iteratively processing each character’s Unicode code point and incorporating it into the hash.
Syntax:
string.split('').reduce((hash, char) => {
return char.charCodeAt(0) + (hash << 6) + (hash << 16) - hash;
}, 0);
Example:
function stringToHash(string) {
return string.split('').reduce((hash, char) => {
return char.charCodeAt(0) + (hash << 6) + (hash << 16) - hash;
}, 0);
}
let gfg = "GeeksforGeeks";
console.log(stringToHash(gfg));
Output
-2465134923
Using bitwise XOR operation
Using a bitwise XOR operation to generate a hash from a string. It iterates over each character, XORs its Unicode value with the current hash, updating it. This approach offers simplicity and efficiency in creating a unique hash.
Example: In this example we are using above-explained approach.
function stringToHash(string) {
let hash = 0;
if (string.length === 0) return hash;
for (const char of string) {
hash ^= char.charCodeAt(0); // Bitwise XOR operation
}
return hash;
}
// String printing in hash
const gfg = "GeeksforGeeks";
console.log(stringToHash(gfg));
Output
123
Approach: Using Crypto library’s createHash() method with SHA-256 algorithm
The Crypto library in Node.js provides a createHash() method that allows generating hash digests using various algorithms, including SHA-256. This method takes the algorithm name as an argument and returns a Hash object, which can then be used to update the hash with data and obtain the hash digest.
Example:
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
Output:
2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824
