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Multiple attribute in Select lists

Posted on 2001-08-20
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Last Modified: 2013-11-19
Can anyone explain why the folling code does not work?
If you press the button once only one option is selected, pressing it twice works fine. Is this a bug in IE and if so is there a work around?

I have experimented with this to the point where if you uncomment out the alert box, it works first time but it is not practicle to have an alert box in the function.

<script language="Javascript">

function SelectAllOptions (theField)
{
     theField.multiple = true ;
     //alert("nothing") ;
     for (x=0; x<theField.options.length; x++)
     {
          theField.options[x].selected = true ;
     }
}
</script>

<form name="test">
<select name="list" size="5">
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<option>Option 4</option>
<option>Option 5</option>
</select>

<input type="button" value="select all options" onclick="SelectAllOptions(this.form.list);">
</form>
0
Comment
Question by:reidca
8 Comments
 
LVL 4

Expert Comment

by:aponcealbuerne
ID: 6406474
try with

<select name="list" size="5" multiple="true">

from the select tag not in the function...


hope helps
0
 

Expert Comment

by:PureSona
ID: 6406523
I changed ur code a little bit & it works fine.


<script language="Javascript">

function SelectAllOptions (theField)
{
    //theField.multiple = true ;
    //alert("nothing") ;
    for (x=0; x<theField.options.length; x++)
    {
         theField.options[x].selected = true ;
    }
}
</script>

<form name="test">
<select name="list" size="5" multiple>
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<option>Option 4</option>
<option>Option 5</option>
</select>

<input type="button" value="select all options" onclick="SelectAllOptions(this.form.list);">
</form>

0
 
LVL 1

Author Comment

by:reidca
ID: 6406529
This does help but the function was designed like that deliberately. It will be used in an application where the user should not be able to select multiple options.
when the form is submitted a JavaScript routine is run that changes the type to multiple and selects all the options for submission to the server.

Thanks anyway.
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LVL 1

Expert Comment

by:james_beilby
ID: 6406742
This should work. The timeout delay's set to 0, but it gives the browser a chance to update the select box multiple value.

<html>
<head>
<script language="Javascript">

function SelectAllOptions(formName,fieldName){
    theField = document.forms[formName].elements[fieldName];
    for (x=0; x<theField.options.length; x++)
         theField.options[x].selected = true;
}

function SetMultiple(listObj){
  listObj.multiple=true;
  setTimeout("SelectAllOptions('"+listObj.form.name+"','"+listObj.name+"')",0);
}
</script>
</head>
<body>
<form name="test">
<select name="list" size="5">
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<option>Option 4</option>
<option>Option 5</option>
</select>

<input type="button" value="select all options" onclick="SetMultiple(this.form.list);">
</form>
</body>
</html>
0
 
LVL 1

Expert Comment

by:james_beilby
ID: 6406791
Just a small update - works the same as the script above except a bit tidier by passing a global object instead of the name references:

<html>
<head>
<script language="Javascript">
<!--
var listObj;

function SelectAllOptions(theField){
   theField.multiple=true;
   listObj = theField;
   setTimeout("SelectAllOptionsCont(listObj)",0);
}

function SelectAllOptionsCont(theField){
   for (x=0; x<theField.options.length; x++)
       theField.options[x].selected = true;
}
//-->
</script>
</head>
<body>
<form name="test">
<select name="list" size="5">
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<option>Option 4</option>
<option>Option 5</option>
</select>

<input type="button" value="select all options" onclick="SelectAllOptions(this.form.list);">
</form>
</body>
</html>
0
 
LVL 1

Author Comment

by:reidca
ID: 6408989
Thanks very much for your help James.
The idea works fine and in the above code it works fine.

The problem I am still having is that I have multiple select lists on a form, all requiring the same feature i.e.not being a multiple select list until just before the form is submitted to the server.

I call the functions one after another i.e.
SelectAllOptions(theForm.MonitoringToolsInstalled) ;
SelectAllOptions(theForm.DiskBays) ;
SelectAllOptions(theForm.HardDiskControllers) ;
SelectAllOptions(theForm.HardDisks) ;
SelectAllOptions(theForm.MemorySlots) ;
SelectAllOptions(theForm.MemoryModules) ;
SelectAllOptions(theForm.ExpansionSlots) ;
SelectAllOptions(theForm.IPAddresses) ;
SelectAllOptions(theForm.NetworkCards) ;

What I am finding is that using the setTimeout method as above causes only the last function call to work correctly because the script is continuing to run after each call to setTimeout. So this code works fine if there is only one call to the function but not when there are many as there are at the moment. Any further thoughts on this would be very much appreciated. Thanks.
0
 
LVL 1

Accepted Solution

by:
james_beilby earned 300 total points
ID: 6409315
Going back to my first script is probably the best option. This way the global listObj is not overwritten by any following calls.

<html>
<head>
<script language="Javascript">
<!--
function SelectAllOptions(listObj){
   listObj.multiple=true;
   setTimeout("SelectAllOptionsCont('"+listObj.form.name+"','"+listObj.name+"')",0);
}

function SelectAllOptionsCont(formName,fieldName){
   theField = document.forms[formName].elements[fieldName];
   for (x=0; x<theField.options.length; x++)
        theField.options[x].selected = true;
}
//-->
</script>
</head>
<body>
<form name="test">
<select name="list" size="5">
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<option>Option 4</option>
<option>Option 5</option>
</select>
<select name="list2" size="5">
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<option>Option 4</option>
<option>Option 5</option>
</select>

<input type="button" value="select all options" onclick="SelectAllOptions(this.form.list);SelectAllOptions(this.form.list2);">
</form>
</body>
</html>
0
 
LVL 1

Author Comment

by:reidca
ID: 6409846
James, I'm going to accept your comment as an answer.
Basically I still have problems with this routine but it's a bit difficult to explain because you can't see the form or the server side code.

Also, the answer you have provided solved the original question so thanks for that.

In the end what I have decided to do is stick to using the multiple attribute in the HTML tag but I have written a routine in Javascript for the OnChange method that detects whether the user has selected more than one option, if so it deselects all options and warns them that this is not supported. Works quite well.

I would spend more time on this but I need to push onto other things. Thanks for your help.
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