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hash-code-string

Overview

hash-code-string is a small utility package to convert long strings into shorter, hash-like strings. It provides functions to create hashes, encode them in a URL-safe base64 format, and decode them back into bytes, or a 32 bit number if desired. Limited to 32 bits of uniqueness. No dependencies, the hashing code is 5 lines. Assumes environment has Uint8Array, Math.imul, and btoa.

Installation

npm install hash-code-string
pnpm install hash-code-string

Usage

import { hashString, hashToNum32 } from 'hash-code-string';

// Example usage
const longString = "This is a long string that needs to be hashed";
const hash = hashString(longString);
console.log(`Hash: ${hash}`); // Hash: g3g2qw

const decodedHash = hashToNum32(hash);
console.log(`Decoded Hash: ${decodedHash}`); // Decoded Hash: -1422493565

API

hashCode(str: string): number

Creates a hash code number from a string similar to Java's String.hashCode method.

Parameters:

  • str: The input string to hash.

Returns:

A 32-bit integer hash code.

num32toBytes(num: number): Uint8Array

Splits a 32-bit number into an array of 4 bytes.

Parameters:

  • num: The 32-bit integer to split.

Returns:

A Uint8Array containing 4 bytes.

codesToString(bytes: Uint8Array): string

Converts an array of byte values to a string.

Parameters:

  • bytes: An array of bytes.

Returns:

A string representing the byte values.

encode64(str: string): string

Encodes a string into a URL-safe base64 format.

Parameters:

  • str: The input string to encode.

Returns:

A URL-safe base64 encoded string.

hashString(str: string): string

Creates a hash of the input string and encodes it in URL-safe base64 format.

Parameters:

  • str: The input string to hash and encode.

Returns:

A URL-safe base64 encoded hash string.

decode64(str: string): string

Decodes a URL-safe base64 string.

Parameters:

  • str: The URL-safe base64 string to decode.

Returns:

The decoded string.

stringToCodes(str: string): number[]

Converts a string to an array of character codes.

Parameters:

  • str: The input string.

Returns:

An array of character codes.

bytesToNum32(bytes: Uint8Array): number

Converts the first 4 elements of a byte array back to a 32-bit number.

Parameters:

  • bytes: An array of bytes.

Returns:

A 32-bit integer.

Example

const str = "example";
const hash = hashString(str);
console.log(hash); // Output: URL-safe base64 encoded hash

const decoded = decode64(hash);
console.log(decoded); // Output: decoded hash string

const charCodes = stringToCodes(decoded);
console.log(charCodes); // Output: Array of character codes

const num = bytesToNum32(charCodes);
console.log(num); // Output: 32-bit number

Contributing

Contributions are welcome! Please open an issue or submit a pull request on GitHub.

License

This project is licensed under the ISC License. See the LICENSE file for details.