add produce example for node.js

Author: hpihkala

examples/node/node-example-produce.js

@@ -0,0 +1,24 @@
+// To enable debug logging:
+// DEBUG=StreamrClient node examples/node.js
+
+const StreamrClient = require('streamr-client')
+
+const STREAM_ID = 'MY-STREAM-ID'
+const API_KEY = 'MY-API-KEY'
+
+// Create the client and give the API key to use by default
+const client = new StreamrClient({
+    restUrl: 'http://localhost:8890/api/v1',
+    apiKey: API_KEY
+})
+
+// Here is the event we'll be sending
+const msg = {
+    hello: 'world',
+    random: Math.random()
+}
+
+// Produce the event to the Stream
+client.produceToStream(STREAM_ID, msg)
+    .then(() => console.log('Sent successfully: ', msg))
+    .catch((err) => console.error(err))