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server.js
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import http from 'http';
import {WebSocketServer} from 'ws';
const port = process.env.PORT || 10000;
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/html');
res.end(`
<!DOCTYPE html>
<html>
<head>
<title>WebSocket Test</title>
</head>
<body>
<h1>WebSocket Test</h1>
<p>Open your browser's developer tools to see the WebSocket messages.</p>
<script>
const socket = new WebSocket('ws://localhost:' + ${port});
socket.onopen = () => {
console.log('WebSocket test connection established');
};
socket.onmessage = (event) => {
console.log('Received message:', event.data);
};
socket.onclose = () => {
console.log('WebSocket connection closed');
};
</script>
</body>
</html>
`);
});
const wss = new WebSocketServer({server});
const rawValue = 1.00; // fictional voltage input value from hardware
let scaledValue = 1.00; // scaled value for gauge display
let fluctuationRange = scaledValue / 20; // range of fluctuation
wss.on('connection', (ws) => {
console.log('WebSocket client connected');
// send websocket data array every 100ms
const sendData = () => {
const data = generateFluctuatingArray(scaledValue, fluctuationRange);
ws.send(JSON.stringify(data));
};
const interval = setInterval(sendData, 100);
// generate array with fluctuating values
const generateFluctuatingArray = (scaledValue, fluctuationRange) => {
const fluctuatingArray = [];
// generate random fluctuation and add to scaledValue
const randomFluctuation =
Math.random() * fluctuationRange * 2 - fluctuationRange;
const av = parseFloat(scaledValue + randomFluctuation);
// calculate the other values relative to av
const absAv = Math.abs(av);
const p = Math.pow(av, 2);
const pp = Math.abs(av) * 2;
const rms = Math.sqrt(Math.pow(av, 2) / 2);
// create the array with the values to display
fluctuatingArray.push(av, absAv, p, pp, rms);
return fluctuatingArray;
};
// calculates the new scaledValue when the user changes the voltmeter range (maxVal)
ws.on('message', (message) => {
console.log('Message sent from client to server: ', message + '\n');
try {
let data = {};
if (message != 'initialData') {
data = JSON.parse(message);
}
if (data.hasOwnProperty('option')) {
if (typeof data.option === 'number') {
const maxValue = Number(data.option);
console.log('range changed by user to: ', maxValue);
console.log('old scaledValue: ', scaledValue);
// calculate the new scaledValue from maxValue and rawValue
scaledValue = Number((rawValue / maxValue).toFixed(2));
// update fluctuationRange
fluctuationRange = Number((scaledValue / 20).toFixed(2));
}
console.log('new scaledValue:', scaledValue);
}
} catch (error) {
console.error('Error parsing JSON message sent from client:', error);
}
});
ws.on('close', () => {
console.log('WebSocket client disconnected');
clearInterval(interval);
});
});
server.listen(port, () => {
console.log('Server running at http://localhost:' + port);
});