Disable browser back button

The browser back button isn't a web standard, it is a convenience provided by your browser so they all implement it in their own way and there is no standard that allows your code to interact with browser features. Your code interacts with HTML, not the container the HTML is in. Let's say you *could* disable the back button....some browsers let you use alt-left, are you going to disable alt-left too? Maybe there is a browser out there somewhere you don't know about that let's you go back using ctrl-shift-b...how do you know that such a browser exists and that you need to add that combo to your list of blocked commands? Let's say one browser uses ctrl-f4 to go back, and if you disable that in one browser you stop another browser being able to close the tab.

You can only control things that are defined via standards, each browser is its own implementation so there is no "container api" that lets you access browser features.

Now let's say you are trying to disable the back button for security reasons...what stops me writing my own browser that ignores any attempt to disable the back button?

You are thinking about your problem from the wrong angle, read the link I posted. You *can't* disable the back button, you have to accept that. So instead explain *why* you want to disable it and someone might have a solution.

This is the perfect answer!
My virtual 5!