newpay-wallet-js/es6/lib/feature_detect/incognito.js

import browser from './browser'
/*
* Using feature detectino techniques described here:
* https://stackoverflow.com/questions/2860879/detecting-if-a-browser-is-using-private-browsing-mode
*/
export default function(cb){
    let ua = navigator.userAgent.toLowerCase();
    let name = browser();
    if(name === "firefox"){
        var db = indexedDB.open("test");
        db.onerror = function(){
            cb(true);
        };
        db.onsuccess =function(){
            cb(false);
        };
    } else if(name === "safari"){
        var storage = window.sessionStorage;
        try {
            storage.setItem("someKeyHere", "test");
            storage.removeItem("someKeyHere");
            cb(false);
        } catch (e) {
            if (e.code === DOMException.QUOTA_EXCEEDED_ERR && storage.length === 0) {
                //Private here
                cb(true);
            } else {
                cb(false);
            }
        }
    } else if(name === "chrome" || name === "opera"){
        var fs = window.RequestFileSystem || window.webkitRequestFileSystem;
        if (!fs) {
            cb(false);
            return;
        }

        fs(window.TEMPORARY, 100, function (fs) {
            // Not incognito mode
            cb(false);
        }, function (err) {
            // Incognito mode
            cb(true);
        });
    } else if(name === "ie"){
        if(!window.indexedDB && (window.PointerEvent || window.MSPointerEvent)){
            //Privacy Mode
            cb(true);
        } else {
            cb(false);
        }
    }
}