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Javascript - Multi select listbox to hide / unhide textbox

Posted on 2008-10-12
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1,583 Views
Last Modified: 2012-06-21
Hi!
I have a multi-select textbox named : LIST_CAT and a textfield named: LIST_CAT_OTHERS that is hidden.

On page load, i will populate the items inside this listbox from database.

I need a javascript such that, when one of the items inside the LIST_CAT is selected - The value is Others, this textfield will  appear.

Any advice on how i can go about doing it?

The reason why i need javascript is because that if i use post back, though the LIST_CAT_OTHERS is visible, the LIST_CAT will display the list from the top again.

Thanks in advance!
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Question by:darenceang
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7 Comments
 
LVL 26

Expert Comment

by:Anurag Thakur
ID: 22697062
If you use postback and do it through javascript it will be perfect - not as fast as through javascript but will not behave as you are anticipating
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LVL 4

Author Comment

by:darenceang
ID: 22700032
But if i do a postback... the listbox will return to the first item yea?
If my listbox containts 15 items...

it will show:
Item 1
item 2
item 3
item 4
item 5

If i browse down and select item 14, the post back will refresh and then it will show item 1 first again... but i want it to "STAY" @ item 14.
0
 

Expert Comment

by:Interlinked
ID: 22700073
Could you just do this via a bit of server side processing? so far example:

<select name="LIST_CAT ">
<option value="1" <%= String(Request("LIST_CAT")) == "1" ? "Selected" : "" %> >Item 1</option>
<option value="2" <%= String(Request("LIST_CAT")) == "2" ? "Selected" : "" %> >Item 2</option>
<option value="3" <%= String(Request("LIST_CAT")) == "3" ? "Selected" : "" %> >Item 3</option>
<option value="4" <%= String(Request("LIST_CAT")) == "4" ? "Selected" : "" %> >Item 4</option>
<option value="5" <%= String(Request("LIST_CAT")) == "5" ? "Selected" : "" %> >Item 5</option>
<option value="6" <%= String(Request("LIST_CAT")) == "6" ? "Selected" : "" %> >Item 6</option>
<option value="7" <%= String(Request("LIST_CAT")) == "7" ? "Selected" : "" %> >Item 7</option>
<option value="8" <%= String(Request("LIST_CAT")) == "8" ? "Selected" : "" %> >Item 8</option>
<option value="9" <%= String(Request("LIST_CAT")) == "9" ? "Selected" : "" %> >Item 9</option>
<option value="10" <%= String(Request("LIST_CAT")) == "10" ? "Selected" : "" %> >Item 10</option>
<option value="11" <%= String(Request("LIST_CAT")) == "11" ? "Selected" : "" %> >Item 11</option>
<option value="12" <%= String(Request("LIST_CAT")) == "12" ? "Selected" : "" %> >Item 12</option>
<option value="13" <%= String(Request("LIST_CAT")) == "13" ? "Selected" : "" %> >Item 13</option>
<option value="14" <%= String(Request("LIST_CAT")) == "14" ? "Selected" : "" %> >Item 14</option>
</select>

This is just to run in Javascript ASP,but I can adapt to another language if you know what your server can support.
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LVL 4

Author Comment

by:darenceang
ID: 22700110
Hi Interlinked.

What u mean by that?
Sorry... noob....

Do u mean that after my onSelectedIndexChange, i repopulate the list again?
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Expert Comment

by:Interlinked
ID: 22700139

I think i am miss understanding... are you trying to get the text box "LIST_CAT_OTHERS" to show when the user selects the value "Others" from LIST_CAT?

If so, you could do:
function ShowList_Cat_Others() {
 if (document.getElementById("LIST_CAT").value) == "Others") { document.getElementById("LIST_CAT_OTHERS").style.display = ''; }
}

<select name="LIST_CAT " id="LIST_CAT" onchange="ShowList_Cat_Others()">....</select>

if you set the textfield LIST_CAT_OTHERS to load with the display:none as a style, then it will be hidden when it loads and showing when the user select the "Other".

The example i gave below will work if someone is posting the data back to your server and you want them to reload with the last option they had selected still being selected.
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LVL 4

Author Comment

by:darenceang
ID: 22700217
Hi Interlinked.
I tried ur codes. but there is no such thing as .value

Do i have to use a for loop since its a multi-select listbox?

Please advice.
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Accepted Solution

by:
Interlinked earned 50 total points
ID: 22702160

Sorry, I should have put:

function ShowList_Cat_Others() {
 if (String(document.getElementById("LIST_CAT").options[document.getElementById("LIST_CAT").selectedIndex].value) == "Others") { document.getElementById("LIST_CAT_OTHERS").style.display = ''; }
}


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