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[JavaScript] onbeforeunload with exception

Asked by James Rose,

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James Rose

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Posted

I am working on a site that places orders and mgmt wants an alert when the user attempts to leave the site so that they don't lose their order. So of course the base answer is to use the "onbeforeunload" function. This is fine, except that there are "a href" tags that call JavaScript functions on the page (no way around this) So what I'm attempting to do is to find a way around. I have a variable (mbBeforeUnload) that is set when an item has been added to the order. But other than that I have not been able to find a way around this issue.

Code:

window.onbeforeunload = checkBeforeUnload;

function checkBeforeUnload(){

if (mbBeforeUnload){

return "The order will be lost if you navigate away from this page.";

}

}

Any thoughts?

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nihal

Posted
Posted

you are defining checkBeforeUnload after calling it...

chk out this example:

<HTML>
<head>
<script>
function closeIt()
{
  return "Any string value here forces a dialog box to \n" + 
		 "appear before closing the window.";
}
window.onbeforeunload = closeIt;
</script>
</head>
<body>
  <a href="http://www.microsoft.com">Click to navigate to 
	  www.microsoft.com</a>;
&lt;/body&gt;
&lt;/html&gt;

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James Rose

Posted
  • Author
Posted

Thanks, but that's not it at all. The function works as it should, I would like to be able to avoid triggering the call in specific cases. The "onbeforeunload" function is called for any <a> link and I have a few links that are just JavaScript calls.

The code below is simply lines taken out of context to show everyone what is being done. The variable "mbBeforeUnload" is set to true when any item is added to the order. So when the user selects a link after an item has been added the variable is true and the call is made. I have tried to temporarily reset the variable in the called function such as:

function test():{

mbBeforeUnload=false;

//do some other code

mbBeforeUnload=true;

}

But this still causes onbeforeunload to fire.

Thanks kindly nihal for the input. Any other ideas? Anyone?

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James Rose

Posted
  • Author
Posted

Yes I am calling a function using the "onclick"

Code:

<a href="java script:void(0)" onclick="ShowReviewSubmit();">3. Review & Submit</a>

So by this time the user has added one or more items and they want to review before accepting the order. All that does is hide and show some divs.

Thanks again for the feedback. If you're ever in the VB world and need help, feel free to ask. I've used that for 16 years, but JavaScript is new to me.

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Grand Master

Rob Veteran

Posted
  • Veteran
Posted

Try this:

&lt;html&gt;
&lt;head&gt;
&lt;script&gt;
var preventPrompt = false;

function closeIt() {
  if(needsPrompt) {
	return "You sure?";
  }
  preventPrompt = false;
}
window.onbeforeunload = closeIt;
&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;
  &lt;a href="http://www.google.com" onclick="preventPrompt=true;"&gt;A link that will be allowed regardless.&lt;/a&gt;
&lt;/body&gt;
&lt;/html&gt;

We're using the onclick event to set a variable. This variable is checked in the closeIt() method to see whether we should allow the request to go through unhindered. Regardless of the outcome, we then set this variable to false again, so other browser actions will be intercepted.

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James Rose

Posted
  • Author
Posted

Rob,

Thanks but I'm using the onclick to run a javascript function. There is no real href.

&lt;a href="java script:void(0)" onclick="ShowReviewSubmit();"&gt;3. Review &amp; Submit&lt;/a&gt;

The first post mentions that I already use a variable "mbBeforeUnload" so that the unload only activates if the user has added items to the order. But unfortunatly the "window.onbeforeunload" function is activated on any a href, even if there is no url. (arg) I have tried resetting the variable in the called function such as:

function test():{
mbBeforeUnload=false;
//do some other code
mbBeforeUnload=true;
}

But that doesn't work. (double arg) So again, thanks kindly, but I need a diff answer.

Have a great long weekend (if you're here in the US, if not, well, ditch work/school, have some fun!)

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Grand Master

Rob Veteran

Posted
  • Veteran
Posted (edited) 

&lt;html&gt;
&lt;head&gt;
&lt;script&gt;
var preventPrompt = false;
var careAboutPrompting = true;

function closeIt() {
  if(!preventPrompt &amp;&amp; careAboutPrompting) {
	return "You sure?";
  }
  preventPrompt = false;
}

function specialEvent() {
  alert("Our special event has been called, without triggering the closeIt() method.");
  return false;
}

window.onbeforeunload = closeIt;
&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;

&lt;a href="#" onclick="preventPrompt=true;specialEvent();"&gt;Do something special.&lt;/a&gt;
&lt;/body&gt;
&lt;/html&gt;

This really seems to do what you're asking unless I'm really mistaken. The careAboutPrompting variable in this example is basically akin to your mbBeforeUnload variable, set to true when you actually give a damn about the user possibly navigating away. The 'Do Something Special' link calls a JavaScript event, but the beforeunload event isn't acted upon.

Edited by Rob
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