Bun.sh - function to get GitHub-style hash for file

index.ts

// When you are using GitHub Api to get contents from repository, 
// file hashes will be different than hashes you get with 'sha1sum'.
// This example shows how you can get same hashes using Bun.sh

import { CryptoHasher } from 'bun';

async function getGitFileHash(filePath: string): Promise<string> {
  const file = await Bun.file(filePath).arrayBuffer();
  const content = new Uint8Array(file);

  const header = `blob ${content.length}\0`;
  const headerArray = new TextEncoder().encode(header);

  const fullContent = new Uint8Array(headerArray.length + content.length);
  fullContent.set(headerArray);
  fullContent.set(content, headerArray.length);

  const hasher = new CryptoHasher('sha1');
  hasher.update(fullContent);
  return hasher.digest('hex');
}

const fileHash = await getGitFileHash('default.sh');

console.log(fileHash);