IoT_Lab_Final/client/index.js

const io = require('socket.io-client');
const socket = io('http://localhost:3000');

let timeFlag; // Flag to keep track of time passed
let prevData; // Object to store and compare previously sent data

socket.on('connect', () => {
    console.log('Connected to server!'); // Client connects to server

    // Only happens the first time the client connects to the server
    timeFlag = new Date();
    prevData = {
        temperature: getTemp(),
        humAir: getHumAir(),
        humGround: getHumGround(),
        airSpeed: getAirSpeed(),
    }
});

setInterval(() => {
    let data = {
        temperature: getTemp(),
        humAir: getHumAir(),
        humGround: getHumGround(),
        airSpeed: getAirSpeed(),
    }

    const now = new Date();
    let timeDiff = now - timeFlag;
    timeDiff /= 1000;

    // If more than 5 minutes have passed or compareData is true
    if ((timeDiff > 5) || compareData(data)) {
        prevData = data;
        timeFlag = new Date();
        socket.emit('data', data);
    }
}, 2 * 1000); // Every 30s

// Return a test temp from 1-50
getTemp = () => {
    return Math.floor(Math.random() * 50);
}

// Return a test air humidity from 1-100
getHumAir = () => {
    return Math.floor(Math.random() * 100);
}

// Return a test ground humidity from 1-100
getHumGround = () => {
    return Math.floor(Math.random() * 100);
}

// Return a test wind speed from 1-12
getAirSpeed = () => {
    return Math.floor(Math.random() * 12);
}

// Compare data with prevData and determine if they need to be send to server
compareData = (data) => {
    for (const key in data) {
        if (diff(data[key], prevData[key]) > 10)
            return true;
    }
    return false;
}

// Handy function to calculate the % difference
diff = (x, y) => {
    return 100 * Math.abs((x - y) / ((x + y) / 2));
}