sumorobot-web/assets/js/sumorobot.js

// Sumorobot constructor
var Sumorobot = function(wsUri, robotId) {
    // Assign the WebSocket URI
    this.wsUri = wsUri;
    // Assign the SumoRobot ID
    this.robotId = robotId;
    // To keep track of the WebSocket connection
    this.watchdogCounter = 0;
    // When connection was intentionally closed
    this.terminate = false;
    // To store Blockly code
    this.blocklyCode = '';
    // If robot is moving
    this.moving = false;
    // Sensor data
    this.sensors = {
        'opponent': 99,
        'line_left': 0,
        'line_right': 0,
        'battery_voltage': 0
    };
    // Start connecting to the WebSocket
    this.connect();
};

// Function to initiate the WebSocket connection
Sumorobot.prototype.connect = function() {
    // To have access to this object inside events
    var self = this;
    this.websocket = new WebSocket(this.wsUri);
    // Setup connection watchdog interval
    self.connectionTimer = setInterval(function() {
        if (self.watchdogCounter == 0 && !self.terminate) {
            $("#battery img").attr("src", "assets/img/battery_disconnected.png");
        }
        // Reset watchdog counter
        self.watchdogCounter = 0;
    }, 3000);
    // When the WebSocket gets connected
    this.websocket.onopen = function(evt) {
        // Setup a timer to ping the robot
        self.watchdogTimer = setInterval(function() {
            // Send a ping to the robot
            self.send('ping');
        }, 500);
    };
    // When the WebSocket closes
    this.websocket.onclose = function(evt) {
        // Clear the timers
        clearInterval(self.watchdogTimer);
        clearInterval(self.connectionTimer);
        // Try to recnnect to the sumorobot
        // Only if the connection wasn't closed intentionally
        if (!self.terminate) {
            self.connect();
        }
    };
    // When there is a message from the WebSocket
    this.websocket.onmessage = function(evt) {
        // When scope is received
        var data = evt.data.replace(/'/g, '"').toLowerCase();
        // Get SumoRobot battery voltage
        self.sensors = JSON.parse(data);
        // When sensor data received
        if (self.sensors['battery_voltage']) {
            if (self.sensors['battery_voltage'] > 4.0) {
                $("#battery img").attr("src", "assets/img/battery_full.png");
            } else if (self.sensors['battery_voltage'] > 3.1) {
                $("#battery img").attr("src", "assets/img/battery_half.png");
            } else {
                $("#battery img").attr("src", "assets/img/battery_empty.png");
            }
        }
        // Count data received packets
        self.watchdogCounter += 1;
    };
    // When there is an WebSocket error
    this.websocket.onerror = function(err) {
        console.log('ERROR websocket error: ' + err);
    };
};

// Function to send WebSocket data
Sumorobot.prototype.send = function(cmd, val) {
    if (cmd !== 'ping' && cmd !== 'stop') {
        this.moving = true;
    } else {
        this.moving = false;
    }
    // Ready state constants: CONNECTING 0, OPEN 1, CLOSING 2, CLOSED 3
    // https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
    if (!this.terminate && this.websocket.readyState == 1) {
        if (val) {
            this.websocket.send(`{"cmd": "${cmd}", "val": "${val}"}`);
        } else {
            this.websocket.send(`{"cmd": "${cmd}"}`);
        }
    }
};

// Function to close the WebSocket connection
Sumorobot.prototype.close = function() {
    this.terminate = true;
    // Close the WebSocket connection
    this.websocket.close();
};