In my form users are required to select a file from the server, they do so by clicking a browse button which opens a file browser.
Once they have selected a file, the path to the file is returned to a hidden field as its value.
When a file has been selected I'd like this browse button image to change to show the user that their selection has been logged.
I've created a function which checks the value of this hidden field and providing it isn't blank, will change the src of the image button. This function is working ok.
What I'm trying to figure out is where to call the function so it checks the hidden field at the right time. I've tried giving the hidden field an onblur="" and calling my function here but this isn't working.