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// https://dev.to/ratmd/simple-proof-of-work-in-javascript-3kgm
export default function process(
data,
difficulty = 5,
signal = null,
progressCallback = null,
_threads = 1,
) {
console.debug("slow algo");
return new Promise((resolve, reject) => {
let webWorkerURL = URL.createObjectURL(new Blob([
'(', processTask(), ')()'
], { type: 'application/javascript' }));
let worker = new Worker(webWorkerURL);
const terminate = () => {
worker.terminate();
if (signal != null) {
// clean up listener to avoid memory leak
signal.removeEventListener("abort", terminate);
if (signal.aborted) {
console.log("PoW aborted");
reject(false);
}
}
};
if (signal != null) {
signal.addEventListener("abort", terminate, { once: true });
}
worker.onmessage = (event) => {
if (typeof event.data === "number") {
progressCallback?.(event.data);
} else {
terminate();
resolve(event.data);
}
};
worker.onerror = (event) => {
terminate();
reject(event);
};
worker.postMessage({
data,
difficulty
});
URL.revokeObjectURL(webWorkerURL);
});
}
function processTask() {
return function () {
const sha256 = (text) => {
const encoded = new TextEncoder().encode(text);
return crypto.subtle.digest("SHA-256", encoded.buffer)
.then((result) =>
Array.from(new Uint8Array(result))
.map((c) => c.toString(16).padStart(2, "0"))
.join(""),
);
};
addEventListener('message', async (event) => {
let data = event.data.data;
let difficulty = event.data.difficulty;
let hash;
let nonce = 0;
do {
if (nonce & 1023 === 0) {
postMessage(nonce);
}
hash = await sha256(data + nonce++);
} while (hash.substring(0, difficulty) !== Array(difficulty + 1).join('0'));
nonce -= 1; // last nonce was post-incremented
postMessage({
hash,
data,
difficulty,
nonce,
});
});
}.toString();
}
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