Add script to get balance of an account

balance/index.js

+const { ApiPromise, WsProvider } = require('@polkadot/api');
+const readline = require('readline');
+require('dotenv').config();
+
+const ALICE = '6a6XHUGV5mu33rX1vn3iivxxUR4hwoUapsuECGyHpPzfaNtt';
+
+/**
+ * Connect to an xx network node using websocket
+ * @return {Promise} 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 main () {
+    // Connect to the node
+    const api = await connect();
+
+    // Get account data
+    const data = await api.query.system.account(ALICE);
+
+    // Total balance is sum of free and reserved
+    const balance = data.data.free.add(data.data.reserved);
+
+    console.log(balance.toString());
+
+    // Get account data at a past block (wait 20 seconds to let some blocks be produced)
+    await new Promise(r => setTimeout(r, 20000));
+    const hash = await api.rpc.chain.getBlockHash(2);
+    const apiAt = await api.at(hash);
+    const pastdata = await apiAt.query.system.account(ALICE);
+    const pastBalance = pastdata.data.free.add(pastdata.data.reserved);
+
+    console.log(pastBalance.toString());
+}
+
+main().catch(console.error).finally(() => process.exit());

balance/package.json

+{
+  "name": "balance",
+  "version": "1.0.0",
+  "description": "Get the balance of an account",
+  "main": "index.js",
+  "repository": "github.com/xx-labs/scripts/balance",
+  "author": "xx labs",
+  "license": "MIT",
+  "scripts": {
+    "start": "WS_CHAIN='ws://localhost:63007' node index.js"
+  },
+  "dependencies": {
+    "@polkadot/api": "^7.15.1",
+    "dotenv": "^16.0.0"
+  }
+}