3 ms·

This has absolutely been used "in the wild". One particularly nasty strain of ad-block-evasion scripts would detect the developer tools being opened, and would

• sroussey 5y ago
  Way back when, we thought about this for Firebug. One thing that came out of it was browsers started adding the console object (also because devs forgot to remove the calls on it). Even so, we added CSS and stuff to highlight elements and that was easily found. What do people look for today?
  • duskwuff 5y ago
    The two big ones are: 1. Watching window.innerHeight/innerWidth for sudden, large decreases, indicating that the user just opened the inspector. 2. Logging objects to the console with toString methods and checking if that method gets called.
    • hutzlibu 5y ago
      1. should be trivial to avoid, by opening dev tools in a new window but 2. I have no idea, except the browser vendors would add a "stealth dev mode"
      • petre 5y ago
        2. JSON.stringify(object)
        • hutzlibu 5y ago
          But isn't the point that you want to detect what the foreign code does? So your solution would require inject your code into the code that wants to hide from you ... ?
          • lmm 5y ago
            I think the idea is you patch the console to display the objects without calling their toString methods.
            • BoorishBears 5y ago
              I don't think that works I might be off here, but I imagine console.log early exits if there's no console open, so it doesn't call toString If that's the case you can just write to the console in a loop and immediately know if one is open
              • lmm 5y ago
                > I might be off here, but I imagine console.log early exits if there's no console open, so it doesn't call toString The point is to avoid calling toString when the console is open, by using some other way of displaying logged values.
                • BoorishBears 5y ago
                  I'm saying you can't avoid calling toString. Their code will call console.log(object) every X ticks. As soon as you open the console, console.log fires instead of early exiting => object.toString is called => they know the console is open
                  • sroussey 5y ago
                    Well… you can on a lot of things. We never did .toString() on a whole lot. However, I was big on .displayName (as an override on .name which is found on functions) My memory is fuzzy, but I also had a different function I would call if frameworks added it so instead of “Object {}” it was “Backbone.Model {id=1}”. I put these in and used them in firebug extensions I wrote for frameworks. Later I asked chrome to add something, which is why there is a “enable custom formatters” option for the console. Really needs to work in the debugger though.
      • joombaga 5y ago
        For 2 my first thought is the opposite. Fire the detected method even if devtools isn't opened.
    • DaiPlusPlus 5y ago
      1. That could also be triggered by browser sidebar windows opening though. All of my browsers open dev-tools in a separate window so this is far from foolproof. 2. Ahhh, clever!
• BoorishBears 5y ago
  The ad-block thing is where I first saw it, that and DRM for less-than-legal sites to prevent downloading (stops streaming if the dev console is open) I mean more specifically taking advantage of the awkward UI to cover up your tracks on local storage, it's something that's just devious enough that if you get caught (which is not difficult) it'll be hard to explain what you were doing, and you'll be trying to explain it to technical people