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Exercise 2.1 - Lights and Buttons

f) Random colors

This is the console. All output created with writeLog() is shown here.

Press the RGB LED button (hardware) to change the LED's color randomly between green, red, blue and orange with every click of the button.

script.js

This is the JavaScript code behind the above application.

/* global log, getInput, tf */
writeLog("Solution for exercise 2.1 f) Random colors");
// Create a global variable to store the found devices
var devices;
var led;
var button;
// Initialite connected devices
tf.initDevices(initDone);
// Call this when all connections are established
function initDone(connectedDevices) {
if (connectedDevices.length === 0) {
 writeLog("Oops, didn't find any devices! Make sure they are connected and refresh this page!");
 }
// Store the devices on the global variable
 devices = connectedDevices;
// Get the LED light
 led = devices.getDeviceByIdentifier(271);
// Get the LED button
 button = devices.getDeviceByIdentifier(282);
// Turn both LEDs off initially
 led.off();
 button.off();
// Get notified when the button is pressedn
 button.registerListener(buttonPressed);
}
function buttonPressed(buttonEvent) {
 var buttonState = buttonEvent.getValue("button_state");
// When the state is RELEASED, the button must have been pressed before
 if (buttonState === "RELEASED") {
// Generate an integer random number between 0 and 3
 var r = Math.floor(Math.random() * 4);
 writeLog("The random number is " + r);
switch (r) {
 case 0:
 led.setColor(0, 255, 0);
 break;
 case 1:
 led.setColor(255, 0, 0);
 break;
 case 2:
 led.setColor(0, 0, 255);
 break;
 case 3:
 led.setColor(255, 127, 0);
 break;
 }
 }
}