OS X Yosemite Javascript for Applications (JXA): Toggling background, dark mode, and screen color inversion between day ⇄ night settings

JXA_UIToggle.applescript

function run() {
	// Rob Trew 2015
	// Ver 0.01

	// UI day/night toggling through OS X 10.10 JXA Javascript for Automation


	// SWITCH FROM DAY-TIME DARK MENU BAR AND DOCK WITH DARK BACKGROUND
	// TO NIGHT-TIME *ALL DARK* 
	// (TOGGLE MODE AND BACKGROUND TO BRIGHT, THEN INVERT ALL)

	// Edit to your preferred settings for day and night here:

	var dctSettings = {
		darkMode: { // System Preferences > General > Use dark menu bar and dock
			day: true,
			night: false
		},
		invert: { // System Preferences > Accessibility > Display > Invert Colors
			day: 0,
			night: 1
		},
		background: {
			day: "/Library/Desktop Pictures/Solid Colors/Solid Gray Pro Ultra Dark.png",
			night: "/Library/Desktop Pictures/Solid Colors/Solid Gray Light.png"
		}

	};

	var appSE = Application("System Events"),
		appPrefs = Application("System Preferences"),
		chkInvert;

	// Toggle the dark mode and dark background, and record the new mode as [night|day] 
	if (appSE.appearancePreferences.darkMode() === dctSettings.darkMode.day) {
		appSE.appearancePreferences.darkMode = dctSettings.darkMode.night;
		appSE.currentDesktop.picture = dctSettings.background.night;

		strMode = "night";

	} else {
		appSE.appearancePreferences.darkMode = dctSettings.darkMode.day;
		appSE.currentDesktop.picture = dctSettings.background.day;

		strMode = "day";
	}

	// open the Display panel of Universal Access	
	appPrefs.activate();
	appPrefs.panes.byId(
		"com.apple.preference.universalaccess"
	).anchors.byName("Seeing_Display").reveal();



	// read the state of the color inversion checkbox
	chkInvert = appSE.applicationProcesses.byName(
		"System Preferences"
	).windows.byName("Accessibility").checkboxes.byName("Invert colors");


	// and click it if it doesn't match the new [day|night] mode
	if (chkInvert.value() !== dctSettings.invert[strMode]) {
		appSE.click(chkInvert);
	}
	appPrefs.preferencesWindow.close();
	
	return strMode;
}