bitcoin pow in javascript

To implement the Bitcoin Proof-of-Work algorithm in JavaScript, you can follow these steps:

1. Import the crypto-js library, which provides cryptographic functions in JavaScript

index.tsx
const CryptoJS = require("crypto-js");
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2. Define the block header as an object with the required properties: version, previous block hash, merkle root, timestamp, difficulty target, and nonce. For example:

index.tsx
const block = {
  version: 1,
  prevBlockHash: "prevBlockHash",
  merkleRoot: "merkleRoot",
  timestamp: 123456789,
  bits: 486604799,
  nonce: 123456
};
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3. Calculate the hash of the block header using SHA-256 twice:

index.tsx
const header = (
  block.version.toString(16).padStart(8, "0") +
  block.prevBlockHash +
  block.merkleRoot +
  block.timestamp.toString(16).padStart(8, "0") +
  block.bits.toString(16).padStart(8, "0") +
  block.nonce.toString(16).padStart(8, "0")
);
const hash = CryptoJS.SHA256(CryptoJS.SHA256(header));
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4. Check if the hash meets the target difficulty by comparing it with the bits field, which represents the current difficulty level in compact format:

index.tsx
const target = (
  BigInt(parseInt(block.bits.toString(16).padStart(8, "0"), 16)) *
  (2n ** (8n * (3n - 1n)))
);
const hashInt = BigInt("0x" + hash.toString(CryptoJS.enc.Hex));
if (hashInt < target) {
  console.log("Block hash is valid");
} else {
  console.log("Block hash is invalid");
}
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5. If the hash does not meet the target difficulty, adjust the nonce field and repeat the process until a valid hash is found. The nonce is a 32-bit integer that can be incremented or decremented to create a different hash value.

Note that this simplified example does not include the merkle tree calculation or the block reward transaction, which are part of the actual Bitcoin mining process.