Question

QUESTION

How can I detect if a user has checked the box, "prevent this page from creating additional dialogs"?

WHY It’s a problem

If the user has prevented the appearance of confirm boxes, the function confirm('foobar') always returns false.

If the user cannot see my confirmation dialogue boxes confirm('Are you sure?'), then the user can never perform the action.

CONTEXT

So, I use the code like if(confirm('are you sure?')){ //stuff... }. So an auto-response of false from the browser will prevent the user from ever doing stuff. But, if there was a way to detect that the user has checked the box, then I could execute the action automatically.

I think that if the user has disabled the dialogues, then the function should either throw an error, or return true. The function is meant to confirm an action that the user has requested.

Answer 1

As far as I know, this is not possible to do in any clean way as it’s a browser feature, and if the browser doesn’t let you know then you can’t know.

However, what you could do is write a wrapper around confirm() that times the response time. If it is too fast to be human then the prompt was very probably suppressed and it would return true instead of false. You could make it more robust by running confirm() several times as long as it returns false so the probability of it being an über-fast user is very low.

The wrapper would be something like this:

function myConfirm(message){
    var start = new Date().getTime();
    var result = confirm(message);
    var dt = new Date().getTime() - start;
    // dt < 50ms means probable computer
    // the quickest I could get while expecting the popup was 100ms
    // slowest I got from computer suppression was 20ms
    for(var i=0; i < 10 && !result && dt < 50; i++){
        start = new Date().getTime();
        result = confirm(message);
        dt = new Date().getTime() - start;
    }
    if(dt < 50)
       return true;
    return result;
}

PS: if you want a practical solution and not this hack, Jerzy Zawadzki’s suggestion of using a library to do confirmation dialogs is probably the best way to go.