Question

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Can you detect/redirect a back button press through javascript?

I am developing a small web application. In my application I must know when the user clicks the “back” button, so I can run some javascript code. Is there any such way to detect it?

thank you

Answer 1

Ok, so I discovered that the JS API cannot access the history object’s next property without elevated permissions, which got me thinking in another direction.

Form fields are automatically fetched from the browser’s cache, thus holding historic data. while this is true, javascript code is run independently each time.

So I created a small hidden field to hold a timestamp and compare it against the javascript’s generated datatime.

Here is the code, I am sure it can be much better implemented, though time is short:

$(document).ready(function () {
     var date = new Date();
     var clientMiliseconds = date.getTime();
     clientMiliseconds = roundTime(clientMiliseconds);
     var serverTimeStamp = $('#' + '<%= hfTimeStamp.ClientID %>').val();
     serverTimeStamp = roundTime(serverTimeStamp);
     alert(serverTimeStamp == clientMiliseconds);
});


function roundTime(time) {
    time = Math.floor(time);
     //since the server renders the time components a few seconds before the page is downloaded 
     //which also depends on where you assign the date on the serverside 
     //we've got a small inaccuracy of few seconds. we neglect these seconds, assuming that it would take the user
     //a few seconds to click the back button

     time = time / 10000;
     time = Math.floor(time);
     return time;
}