rpi-backlight/example/server.js

A node library to control the backlight of the official Raspberry Pi 7" touch display

const express = require('express');
const app = express();
const backlight = require('rpi-backlight');

app.get('/', (req, res) => {
    res.sendFile('index.html', {root: __dirname })
});

app.get('/screenOn', (req, res) => {
    backlight.powerOn();
    res.send('Screen On' + '<br><a href="/">Back to home page</a>');
});

app.get('/screenOff', (req, res) => {
    backlight.powerOff();
    res.send('Screen OFF' + '<br><a href="/">Back to home page</a>');
});

app.get('/isScreenOn', (req, res) => {
    backlight.isPoweredOn().then((isScreenOn) => {
        if (isScreenOn)
            res.send('Screen is ON <br><a href="/">Back to home page</a>');
        else
            res.send('Screen is OFF <br><a href="/">Back to home page</a>');
    });
});

app.get('/getBrightness', (req, res) => {
    backlight.getBrightness().then((brightnessValue) => {
        res.send('Screen brightness: ' + brightnessValue + '<br><a href="/">Back to home page</a>');
    });    
});

// The screen goes Off at <= 9 brightness value
app.get('/setBrightness/:value', (req, res) => {
    backlight.setBrightness(req.params.value).then(() => {
        return backlight.getBrightness();
    }).then((newBrightnessValue) => {
        res.send('Screen brightness is now: ' + newBrightnessValue + '<br><a href="/">Back to home page</a>');
    }).catch((err) => {
        backlight.getMaxBrightness().then((maxBrightnessValue) => {
            if (req.params.value > maxBrightnessValue) {
                res.send('ERR: Max value is ' + maxBrightnessValue + '<br><a href="/">Back to home page</a>');
            } else {
                res.send('ERR: Min value is 0' + '<br><a href="/">Back to home page</a>');
            }
        });    
    });
});

app.get('/getMaxBrightness', (req, res) => {
    backlight.getMaxBrightness().then((maxBrightnessValue) => {
        res.send('Brightness max value: ' + maxBrightnessValue + '<br><a href="/">Back to home page</a>');  
    }); 
});

/** Server */
app.listen(3000, () => {
    console.log("server up on port: 3000 !");
});