Is it possible to determine if Google Chrome is in incognito mode via a script?
Edit: I actually meant is it possible via user-script, but the answers assume JavaScript is running on a web page. I've re-asked the question here in regards to user scripts.
The functionality of this answer is Chrome version dependant. The most recent comment was this works in v90
Yes. The FileSystem API is disabled in incognito mode. Check out https://jsfiddle.net/w49x9f1a/ when you are and aren't in incognito mode.
Sample code:
var fs = window.RequestFileSystem || window.webkitRequestFileSystem;
if (!fs) {
console.log("check failed?");
} else {
fs(window.TEMPORARY,
100,
console.log.bind(console, "not in incognito mode"),
console.log.bind(console, "incognito mode"));
}