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Community Blog JavaScript IoT: Leveraging JavaScript for IoT Development

JavaScript IoT: Leveraging JavaScript for IoT Development

In this Javascript IoT blog, you will learn to extend objects with new prototypes and understand the concept of variables in Javascript for developing IoT platform.

Smart homes and many other Internet of Things (IoT) applications are rapidly gaining popularity this year, thanks to the rise of technologies such as 5G. More and more products are being labeled as "smart", such as smart watches and TVs, which shows that people have transformed the word "smart" into a way of life.

Common smart home solutions include the device (thing), the cloud, and the application. Some solutions also involve big data and AI. Traditional IoT development emphasizes the sequence; that is, data must be processed sequentially on the device, cloud, and application. Today, based on the "Thing Specification Language (TSL)" of the Alibaba Cloud IoT Platform, the two ends of the IoT development can run in parallel, significantly saving labor and material costs.

It is obviously tempting to run in parallel, but can we go one step further and let all development be handled by one person? The answer is yes! With all the technologies we have at our disposal, we can now easily design and build a smart home by ourselves, similar to building a website. By using the Alibaba Cloud IoT Platform, we can complete a smart home solution with 30 lines of code.

Currently, many Internet developers have stopped at the gate of the IoT due to lack of embedded development capabilities, such as C/C++ language basics. With Embedded Javascript Tool provided by the Alibaba Cloud IoT Platform, device development can be carried out quickly using JavaScript, which seamlessly resolves the biggest problem facing these developers. For embedded developers who are unfamiliar with front-end and back-end development, Alibaba Cloud IoT Platform also provides the "Visual Building" application and other quick-start functions for application development with zero code, greatly reducing the learning required.

In this article, we will use the Embedded Javascript Tool and the Visual Building function of the Alibaba Cloud IoT Development Platform to quickly develop smart home systems that consist of lighting and temperature and humidity meters, with just 30 lines of code.

Enabling the Service

First, apply for an Alibaba Cloud account, then enable and log in to the one-stop development platform, IoT Studio.

Next, Choose Create Project (you can use any name you like) > Device Development > Add Product > Category. Select "Lighting" or "Temperature & Humidity Meter" as required, select Wi-Fi for the communication method, and select Alink for the data format.

Choose Device Development > Add Debugging Devices, and note the device trituples.

Device Development

Open the embedded JavaScript online workbench (the development environment does not need to be built) and create a new project. Replace the index.js code:

Lighting

var deviceShadow = require('deviceShadow');
var ledHandle = GPIO.open("led1");

deviceShadow.bindDevID({
  "productKey": "123",
  deviceName: "",
  deviceSecret: ""
});

function main(err){
  if(err){
    console.log("failed to connect to the platform");
  }else{
    console.log("the main program started");
    deviceShadow.addDevSetPropertyNotify("LightSwitch", function (lightStatus) {
      GPIO.write(ledHandle, 1-lightStatus);
    });
    var mainLoop = setInterval(function () {
      var ledStatus = GPIO.read(ledHandle);
      deviceShadow.postProperty("LightSwitch", 1-ledStatus);
    }, 2000);
  }
}

deviceShadow.start(main);

You can review Completing a Smart Home System with 30 Lines of JavaScript Code to get the following code.

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Prototypes in JavaScript

It is assumed that you already are acquainted with object data types in JS, creating objects and how to modify object properties. Prototypes allow us to extend objects based on the fact that each JavaScript object includes [[Prototype]] as an internal property.

Inheritance

JavaScript initially searches on an object whenever you attempt to access its property or method, and if not found, it then proceeds to in its [[Prototype]]. If there still are no matches for the property at the [[Prototype]], JavaScript then tries checking from the linked object's prototype until all objects in the chain are all covered n the search. Each chain contains Object.prototype at the end, whereby, there is an inheritance of methods and properties from Object. Searching beyond the chain always returns a null output. In our case above we have an empty object x, that bears inheritance from Object.

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