worker.js

var targetText;
var totalAdrs = 0;
onmessage = function(e) {
    let incoming = JSON.parse(e.data);
    if (incoming.status === "start"){
        targetText = incoming.text;
        if (incoming.data.caseSensitive === false)  targetText = targetText.toLowerCase();
        while (true){
            totalAdrs ++;
            if (totalAdrs % 100 === 0) {
                let datax = {
                    status: "data-dump",
                    totalAdrs: "new 100"
                }
                postMessage(JSON.stringify(datax))
            }
            let wallet = generateKeyPairs();
            let address = wallet.address;
            if (incoming.data.caseSensitive === false) address = address.toLowerCase();
            if (incoming.data.anywhere === true && address.includes(targetText)){
                    let data = {
                        status: "found",
                        address: wallet.address,
                        secret: wallet.privateKey,
                        xPub: wallet.publicKey
                    }
                    return postMessage(JSON.stringify(data))
            }else{
                if (incoming.data.mode === "prefix" && address.slice(1).startsWith(targetText)){
                        let data = {
                            status: "found",
                            address: wallet.address,
                            secret: wallet.privateKey,
                            xPub: wallet.publicKey
                        }
                        return postMessage(JSON.stringify(data))
                }else if (incoming.data.mode === "suffix" && address.endsWith(targetText)){
                        let data = {
                            status: "found",
                            address: wallet.address,
                            secret: wallet.privateKey,
                            xPub: wallet.publicKey
                        }
                        return postMessage(JSON.stringify(data))
                }
            }
        }
    }
  };

  function generateKeyPairs() {
    const bitcoin = require("bitcoinjs-lib");
    const BitcoinjsNetwork = bitcoin.networks.bitcoin
    const keyPair = bitcoin.ECPair.makeRandom({ network: BitcoinjsNetwork });
    const { address } = bitcoin.payments.p2pkh({ pubkey: keyPair.publicKey, network: BitcoinjsNetwork });
    const publicKey = keyPair.publicKey.toString("hex");
    const privateKey = keyPair.toWIF();
    return { address, privateKey, publicKey };
}