Fake Screen Resolution with Nightmarejs

fake_resolution.js

/*
Credits and more resources:
https://gist.github.com/emenoh/65708b03f1a99d92f14db9b0d60d8fd0
https://chromium.googlesource.com/chromium/blink-public/+/master/web/WebDeviceEmulationParams.h
*/

const Nightmare = require('nightmare');

Nightmare.action('emulateDevice',
    (name, options, parent, win, renderer, done) => {
        parent.respondTo('emulateDevice', (settings, done) => {
            win.webContents.on('did-get-response-details', () => {
                win.webContents.enableDeviceEmulation(settings);
            });
            done();
        });
        done();
    },
    function(settings, done) {
        this.child.call('emulateDevice', settings, done);
    });

const mobilesettings = (CustomWidth, CustomHeight) => ({
    
    // https://chromium.googlesource.com/chromium/blink-public/+/master/web/WebDeviceEmulationParams.h
    // screenPosition can either be Desktop or Mobile, if it's Mobile, then custom dimensions are used

    screenPosition: 'mobile',

    screenSize: {
        width: CustomWidth,
        height: CustomHeight
    },

    viewSize: {
        width: CustomWidth,
        height: CustomHeight
    },

    deviceScaleFactor: 0,

    viewPosition: {
        x: 0,
        y: 0
    },

    fitToView: true,

    offset: {
        x: 0,
        y: 0
    }
})

let nightmare = Nightmare({
      show: true
    });

nightmare
    .then(() => {
        return nightmare.emulateDevice(mobilesettings(800, 600))
            .goto("http://www.whatismyscreenresolution.com/")
            .wait()
            .screenshot("TEST_1_.png")
        // more actions here
    })
    .then(() => {
        return nightmare.emulateDevice(mobilesettings(1000, 600))
            .goto("https://browserleaks.com/javascript")
            .wait()
            .screenshot("TEST_2_.png")
        // more actions here
    })
    .then(() => {
        return nightmare.emulateDevice(mobilesettings(1200, 600))
            .goto("http://mydevice.io/")
            .wait()
            .screenshot("TEST_3_.png")
        // more actions here
    })
    .then(() => {
        return nightmare.emulateDevice(mobilesettings(800, 600))
            .goto("http://www.screenresolution.org/")
            .wait()
            .screenshot("TEST_4_.png")
        // more actions here
    }).then(() => {
        return nightmare.end().then(()=>{
          console.log('Finished faking instance life, It was a tough road!')
        })
        // more actions here
    })