keeweb/app/scripts/comp/focus-detector.js

const FeatureDetector = require('../util/feature-detector');
const Launcher = require('../comp/launcher');

const FocusDetector = function () {
    this.isFocused = true;
    this.detectsFocusWithEvents = !FeatureDetector.isDesktop && !FeatureDetector.isMobile;
    if (this.detectsFocusWithEvents) {
        window.onblur = () => { this.isFocused = false; };
        window.onfocus = () => { this.isFocused = true; };
    }
};

FocusDetector.prototype.hasFocus = function () {
    if (this.detectsFocusWithEvents) {
        return this.isFocused;
    } else if (Launcher) {
        return Launcher.isAppFocused();
    } else {
        return true;
    }
};

module.exports = FocusDetector;