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ADD OPTIONS DYNAMICALLY TO SELECTBOX

Posted on 2004-10-19
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Last Modified: 2008-03-10
i have 3 checkboxes
and a selectbox
if the checkboxes are checked some values need to be populated in the selectbox
but if the selectbox has that value already it should not add them.

suppose checking the checkboxA u shud add options a,b,c,d
checking checkboxB u shud add options b,c,d,e
checking checkboxC u shud add options d,e

if both checkbox A and B are checked the values in the selectbox shud not be repeated
and when u uncheck suppose checkboxB the option e should be removied not b c or d as they r in checkboxA

Thanks
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Question by:archrajan
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3 Comments
 
LVL 14

Accepted Solution

by:
RichieHindle earned 500 total points
ID: 12351959
Here you go.  This is a self-contained web page that implements your spec:

<html>
<head>
<script>
// The values for each checkbox.
var list = [ ['a', 'b', 'c', 'd'],      // Checkbox A
             ['b', 'c', 'd', 'e'],      // Checkbox B
             ['d', 'e'] ]               // Checkbox C

// Whether each of the three checkboxes is checked.
var checked = [false, false, false]

// Function to empty a selectbox.
function emptyselectbox(selectbox)
{
   while (selectbox.options && selectbox.options.length > 0)
   {
      selectbox.remove(0)
   }
}

// Function to add to a selectbox.
function addtoselectbox(selectbox, list)
{
    var opt = document.createElement("OPTION")
    opt.text = value
    opt.value = value
    selectbox.add(opt)
}

// Handler for checkboxes being clicked.
function onClick(checkbox, index)
{
    // Get the selectbox and empty it.
    var selectbox = document.selectform.selectbox
    emptyselectbox(selectbox)
   
    // Update the array describing which checkboxes are checked.
    checked[index] = checkbox.checked
   
    // For each checkbox, if it's checked, add its values to the dictionary.
    add = {}
    for (var i=0; i < list.length; i++)
    {
        if (checked[i])
        {
            for (var j = 0; j < list[i].length; j++)
            {
                add[list[i][j]] = true
            }
        }
    }
   
    // Add the values to the selectbox.
    for (value in add)
    {
        addtoselectbox(selectbox, value)
    }
}
</script>
</head>

<body>

<form name='selectform' action='something' method='GET'>
<input type='checkbox' name='A' value='Checkbox A' onclick='onClick(this, 0); return true'>
<input type='checkbox' name='B' value='Checkbox A' onclick='onClick(this, 1); return true'>
<input type='checkbox' name='C' value='Checkbox A' onclick='onClick(this, 2); return true'>
<select name='selectbox'></select>
</form>

</body>
</html>
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LVL 36

Expert Comment

by:Zyloch
ID: 12352593
@Richie,

For adding to a select box, all you need to do is:

function addtoselectbox(selectbox, list)
{
    selectbox.options[selectbox.options.length] = new Option('new text','new value');
}
0
 
LVL 14

Expert Comment

by:RichieHindle
ID: 12355517
Zyloch: Thanks - I didn't know that.  8-)
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