Question

[EASY] Can't find a JavaScript bug in only 5-6 lines of code! Help me to fix it!

Asked by: Collis_Dam

Hello!

Please help me to correct my JavaScript code, because it doesn't work.

The theory: if a textbox changed, and the user wants to go back -> alert about the unsaved changes

I've cut out the unnecessary parts, to shorten the code, so you should focus only on the JS.

<html>
<head>
<script type="text/javascript">
<!--
function onChange() {
var changed = true;
}
 
function confirmation() { 
	var alert = confirm("Warning! You have some unsaved changes! Click on Cancel to ....");
	if (alert){
		window.location = "admin.php";
	}
}
 
function checkChanges() {
if (changed) { confirmation() }
else { window.location = "admin.php"; }
}
//-->
</script>
</head>
<body>
<form>
<input type="text" value="some text" onChange="javascript: onChange()"><br>
<input type="text" value="some other text" onChange="javascript: onChange()"><br>
<input type="button" onclick="checkChanges()" value="Back to admin">
<input type="button" value="Save">
</form>
</body>
</html>
                                  
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Asked On
2009-07-16 at 18:10:21ID24577738
Tags

easy javascript script bug debug

Topics

JavaScript

,

Scripting Languages

,

Debugging Software for Development

Participating Experts
2
Points
50
Comments
6

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Answers

 

by: ZylochPosted on 2009-07-16 at 18:15:02ID: 24875257

There are a few other things I would change, but it seems at a glance the piece that's making it fail is that you haven't defined changed to be global.

Put this above all your function definitions:

var changed = false;

Then, change this line:

var changed = true;

to

changed = true;

 

by: coolersportPosted on 2009-07-16 at 18:15:05ID: 24875258

When you put var changed = true inside onChange(), you are actually defining an inner variable, not global. Therefore when you need to use it in other functions, it implies a new variable with default value to false.

See my suggestion by moving the declaration of changed variable into global scope.

Cheers,
Tien

<html>
<head>
<script type="text/javascript">
<!--
var changed = false;
 
function onChange() {
    changed = true;
}
 
function confirmation() { 
        var alert = confirm("Warning! You have some unsaved changes! Click on Cancel to ....");
        if (alert){
                window.location = "admin.php";
        }
}
 
function checkChanges() {
if (changed) { confirmation() }
else { window.location = "admin.php"; }
}
//-->
</script>
</head>
<body>
<form>
<input type="text" value="some text" onChange="javascript: onChange()"><br>
<input type="text" value="some other text" onChange="javascript: onChange()"><br>
<input type="button" onclick="checkChanges()" value="Back to admin">
<input type="button" value="Save">
</form>
</body>
</html>

                                              
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by: Collis_DamPosted on 2009-07-16 at 18:29:54ID: 24875319

Thank you, Zyloch and coolersport!
Your solutions are working!

But you both submitted the solution at 16/07/09 06:15 PM.

Sorry for the question, but I am new, and I don't want to make mistakes.
So in this situation what should I do? Accept Zyloch's post only or click on "Accept multiple solutions"?

Yes, I know it is only 50 points, but I would like to be fair. :)

 

by: coolersportPosted on 2009-07-16 at 18:41:21ID: 24875368

I don't mind. Whichever way you choose mate :D

 

by: ZylochPosted on 2009-07-16 at 18:42:44ID: 24875373

Probably a split would be most fair. We both posted at basically the same time.

 

by: Collis_DamPosted on 2009-07-16 at 18:56:19ID: 31604513

50/2=25pts
Wow, a lot of points :D

PS: Sorry but I have a limited account, and that was all of my points. But thank you again! :)

20120131-EE-VQP-002

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