Can I use " window.onbeforeunload " twice in my html document?

Question

I am creating a HTML layout where user can fill the data and save that page in HTML and JSON formats by using "save" and "save as draft" resp. Can i use

window.onbeforeunload

twice in my template.html file to show two different alert messages?

The alerts would show:

• when page is empty and user tries to go to load another page
• when user fills the data in the layout and tries to leave the layout without saving

Answer 1

At first see this example to to understand what will happen if you use it twice, then the idea given bellow

window.onbeforeunload=function()
{ 
    if(form_empty())
        return "Form is empty"; // message for empty form 
    else
        return "Form is not empty"; // message for filled up form 
}

function form_empty()
{
    // check form fields whether the form is empty or not
    // return true if form is empty
    // return false if form is not empty
}