Question

I’m trying to change the innerHTML of a element based on the value of the previous element.

I have the javascript correctly grabbing the current value and everything works correctly in Firefox, Safari, Chrome and Opera. IE is a pain.

sample code:

<form action="soap.php" method="post">
    <select name="circuitproduct" id="circuitproduct" onchange="bandwidthfunction();">
        <option>Dedicated Voice</option>
        <option>Frame Relay</option>
        <option>ATM</option>
        <option>Dedicated Internet</option>
        <option>IP Solutions Private Port</option>
        <option>IP Solutions Enhanced Port</option>
        <option>Private Line – Domestic</option>
        <option>Int’l Private Line</option>
        <option>Qwest Metro Private Line (QMPL)</option>
        <option>Qwest Metro Ethernet Private Line (QMEPL)</option>
    </select><br />
    <select name="term" id="term">
        <option value="1-Year">1-Year</option>
        <option value="2-Year">2-Year</option>
        <option value="3-Year">3-Year</option>
    </select>
    <select id="bandwidth">
    </select>
    <select id="sublooptype">
    </select>
</form>

sample javascript:

function bandwidthfunction() {
var product = document.getElementById('circuitproduct').value;
    if (product == 'Dedicated Voice') {
        document.getElementById('bandwidth').innerHTML = ('<option value="DS-1">DS-1</option><option value="DS-3">DS-3</option><option value="OC-3">OC-3</option><option value="OC-12">OC-12</option>');
        document.getElementById('sublooptype').innerHTML = ('<option value="Special Access">Special Access</option><option>CO MtPt - Special Access</option><option>CPA Special Access</option>');
    }
    else if (product == 'Frame Relay') {
        document.getElementById('bandwidth').innerHTML = ('<option value="DS-1">DS-1</option><option value="DS-3">DS-3</option><option value="OC-3">OC-3</option><option value="OC-12">OC-12</option>');
        document.getElementById('sublooptype').innerHTML = ('<option value="Special Access">Special Access</option><option>CO MtPt - Special Access</option><option>CPA Special Access</option>');
}

Answer 1

Well, first of all you have a closing tag for the select that you try to put inside the select element, which makes the code invalid.

Then there might be a problem with how the select element treats it’s content. When the HTML code is parsed, the select element doesn’t have any child elements, like a regular element does. Instead the options are items in it’s options collection.

If you want to change the items in the select element, change the content of it’s option collection. I.e. to add items, create option objects using the document.createElement method and add to the collection. Example:

var opt = document.createElement('OPTION');
opt.text = 'Choose me';
opt.value = 42;
document.getElementById('bandwidth').options.add(opt);