add cli preview and format code

Author: flolu

.github/preview.gif

@@ -5,6 +5,7 @@
   <br>
   <h1>Node.js Kafka Example</h1>
   <p>Realtime Bitcoin Wallet Tracker Example App with Node.js and Kafka</p>
+  <img width="420px" src="./.github/preview.gif" />
 </div>
 
 # Features
@@ -49,6 +50,10 @@
 
 - http://localhost:8080 (Redpanda Console)
 
+**Notes**
+
+- Fetching the balance might stop working at some point, because [Blockcypher](https://www.blockcypher.com) limits the amount of requests one can send to their API
+
 # Codebase
 
 - [`cli.ts`](cli.ts) (CLI application to read wallet data in realtime)

README.md

@@ -19,8 +19,7 @@ async function main() {
       const url = `${API_URL}/${currency}/main/addrs/${address}/balance`
 
       const {data} = await axios.get(url)
-      const balance =
-        currency === 'btc' ? data.balance / 100000000 : data.balance / 1000000000000000000
+      const balance = currency === 'btc' ? data.balance / 100000000 : data.balance / 1000000000000000000
 
       const payload = JSON.stringify({balance})
       await producer.send({

balance.ts

@@ -33,8 +33,8 @@ ws.on('message', (json: string) => {
 
       process.stdout.write(`Wallet:  ${currency.toUpperCase()}\n`)
       process.stdout.write(`Price:   ${price < 0 ? '...' : formatUSD(Number(price))}\n`)
-      process.stdout.write(`Balance: ${balance < 0 ? '...' : balance}\n`)
-      process.stdout.write(`Value:   ${balance < 0 ? '...' : formatUSD(balance * price)}\n`)
+      process.stdout.write(`Balance: ${balance < 0 || !balance ? '...' : balance}\n`)
+      process.stdout.write(`Value:   ${balance < 0 || !balance ? '...' : formatUSD(balance * price)}\n`)
       process.stdout.moveCursor(0, -OUTPUT_LINES_COUNT)
 
       break

cli.ts

@@ -20,6 +20,6 @@
     "singleQuote": true,
     "bracketSpacing": false,
     "semi": false,
-    "printWidth": 100
+    "printWidth": 110
   }
 }

package.json

@@ -24,10 +24,7 @@ async function main() {
     },
   }
 
-  const wsRef = client.combinedStreams(
-    [`${BTC_USDT_TICKER}@ticker`, `${ETH_USDT_TICKER}@ticker`],
-    callbacks
-  )
+  const wsRef = client.combinedStreams([`${BTC_USDT_TICKER}@ticker`, `${ETH_USDT_TICKER}@ticker`], callbacks)
 
   // setTimeout(() => client.unsubscribe(wsRef), 3000)
 }

price.ts

@@ -42,9 +42,7 @@ async function main() {
 
         if (wallet && wallet.currency === currency) {
           const balance = walletBalances.get(wallet.address) || null
-          ws.send(
-            JSON.stringify({type: 'balance', data: {balance, price: prices[currency], currency}})
-          )
+          ws.send(JSON.stringify({type: 'balance', data: {balance, price: prices[currency], currency}}))
         }
       })
     },