Understanding the Eclipse Paho JavaScript asynchronous client

In Chapter 4, Interacting with Sensors in Java, you learned that the Eclipse Paho project provides an open source client implementation of MQTT, and you worked with its Java client. The project also includes a JavaScript client, also known as the Paho JavaScript client or Eclipse Paho JavaScript client. The web page for the Eclipse Paho project is http://www.eclipse.org/paho. The web page for the Eclipse Paho JavaScript client is http://eclipse.org/paho/clients/js. This JavaScript client provides only a non-blocking (asynchronous) API.

The previous web page uses the Eclipse Paho JavaScript client to allow us to subscribe to topic filters and publish messages to topics. Now, we will use the same JavaScript client in a new web page.

Tip

In this case, you will download the plain library. Take into account that you can also consume the plain library and the minified library from cdnjs.com, as explained in the previously mentioned web...