feat: check sync + if transfer from/to specific address in latest blocks

.gitignore

+# env
+**/.env
+
+# node modules
+**/node_modules
\ No newline at end of file

transfers/.eslintrc.json

+{
+    "env": {
+        "browser": true,
+        "commonjs": true,
+        "es2021": true
+    },
+    "extends": [
+        "airbnb-base"
+    ],
+    "parserOptions": {
+        "ecmaVersion": "latest"
+    },
+    "rules": {
+    }
+}

transfers/index.js

+const { ApiPromise, WsProvider } = require('@polkadot/api');
+require('dotenv').config();
+
+async function wait(ms) {
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
+}
+
+/**
+ * Connect to xxNetwork Public Node thorugh a websocket
+ * @return {api} chain api
+ */
+async function connect() {
+  const provider = new WsProvider(process.env.WS_CHAIN);
+  const api = await ApiPromise.create({
+    provider,
+  });
+  await api.isReady;
+  return api;
+}
+
+async function checkSynching(api) {
+  const health = await api.rpc.system.health();
+  return health.isSyncing.toHuman();
+}
+
+async function getAPI() {
+  // Connect to the node
+  const api = await connect();
+
+  // Wait for node to be synced
+  const isSyncing = await checkSynching(api);
+  if (isSyncing) {
+    api.disconnect();
+    console.log('Node is not synced! Waiting 5 seconds...');
+    await wait(5000);
+    return getAPI();
+  }
+  return api;
+}
+function getTransfers(blockEvents) {
+  const transfers = blockEvents
+    .filter((record) => (record.event.section === 'balances' && record.event.method === 'Transfer'))
+    .map(({ event: { data } }) => ({
+      from: data[0].toHuman(),
+      to: data[1].toHuman(),
+      amount: data[2].toHuman(),
+    }));
+  return transfers;
+}
+
+async function main() {
+  const api = await getAPI();
+
+  const address = '1qnJN7FViy3HZaxZK9tGAA71zxHSBeUweirKqCaox4t8GT7';
+
+  // Subscribe to new blocks
+  console.log('Starting block listener...');
+  const unsub = await api.rpc.chain.subscribeNewHeads(async (header) => {
+  // Get block number
+    const blockNumber = header.number.toNumber();
+    console.log(blockNumber);
+
+    // Get block hash
+    const blockHash = await api.rpc.chain.getBlockHash(blockNumber);
+
+    // Get block events
+    const blockEvents = await api.query.system.events.at(blockHash);
+    const transfers = getTransfers(blockEvents);
+
+    const fromAddr = transfers.some((transfer) => (transfer.from === address));
+    const toAddr = transfers.some((transfer) => (transfer.to === address));
+    if (fromAddr) {
+      unsub();
+      console.log('Found Transfer From Address: ', address);
+    }
+
+    if (toAddr) {
+      unsub();
+      console.log('Found Transfer To Address: ', address);
+    }
+  });
+}
+
+main().catch((err) => console.error(err)).finally(() => process.exit());

transfers/package.json

+{
+  "name": "get-transfers",
+  "version": "1.0.0",
+  "description": "synchronize with chain and analyze the successful transfers of addresses through the node interfaces",
+  "main": "index.js",
+  "license": "MIT",
+  "scripts": {
+    "start": "node index.js"
+  },
+  "devDependencies": {
+    "eslint": "^8.12.0",
+    "eslint-config-airbnb-base": "^15.0.0",
+    "eslint-plugin-import": "^2.25.4"
+  },
+  "dependencies": {
+    "@polkadot/api": "^7.14.3",
+    "dotenv": "^16.0.0"
+  }
+}