Develop Reference

Select selected option by class name

I have 2 select boxes where first is all user selectable but in second selected option is dependant on first select box. Selected value in first option box matches option's class in second select box but values are different. I imagine i need something like:
$('#territory').change(function() {
if($(this).val() == 'EU')
{
$('#territory2').class('EU');
}
How do i select selected option by class name? (There might be more than 1 option with the same class name but it just needs to select any of them).
<select id="territory" name="territory"">
<option value="EU">A</option>
<option value="GB">B</option>
<option value="ALL">C</option>
</select>
<select id="territory2" name="territory2">
<option value="1" class="EU">A</option>
<option value="2" class="GB">B</option>
<option value="3" class="ALL">C</option>
<option value="4" class="ALL">D</option>
</select>

Set the value attribute of the desired <option> element on the value attribute of the <select>:
const territory = document.getElementById("territory"),
territory2 = document.getElementById("territory2");
territory.addEventListener("input", ev => {
territory2.querySelector("."+territory.value).selected = true;
});
<select id="territory" name="territory">
<option value="EU">A</option>
<option value="GB">B</option>
<option value="ALL">C</option>
</select>
<select id="territory2" name="territory2">
<option value="1" class="EU">A</option>
<option value="2" class="GB">B</option>
<option value="3" class="ALL">C</option>
<option value="4" class="ALL">D</option>
</select>
Note that this will only select the first option with that class.

I recommend data-attribute:
$('#territory').on("change", function() {
const territory = $("option:selected", this).data("territory");
$("#territory2").val(territory)
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<select id="territory" name="territory">
<option value="" data-territory="0">Please select</option>
<option value="EU" data-territory="1">A</option>
<option value="GB" data-territory="2">B</option>
<option value="ALL" data-territory="3">C</option>
</select>
<select id="territory2" name="territory2">
<option value="0">Please select</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>

I need a simple dropdown menu OnChange/Select in javascript

I need help on something really simple.
I have 2 dropdown boxes on a form:
<select name="OfficeLocation" >
<option value="" ></option>
<option value="1" selected="selected">New York</option>
<option value="2" >Los Angeles</option>
<option value="3" >San Francisco</option>
</select>
<select name="OfficePhone">
<option value="" ></option>
<option value="1">(718)555-1212</option>
<option value="2" >(213)555-1212</option>
<option value="3" >(415)555-1214</option>
</select>
The second one is "Read Only"
All I need to know is how can I change the value of "OfficePhone" by changing the value of "OfficeLocation"? using either a simple JavaScript or JSP Command
Thanks

You are able to use a script like the following:
<script>
menu1 = document.getElementsByName('OfficeLocation')[0];
menu2 = document.getElementsByName('OfficePhone')[0];
menu1.onchange = function(){
menu2.value = menu1.value;
}
</script>
Here you are using the onchange event to initiate a function that make the value on the second menu menu2 equals to the selected value of the first menu menu1.
An online demo is here
Notice that: the script should be placed after your elements.

You gonna need an event handler function for the OfficeLocation select and an id for the second select.
<select name="OfficeLocation" onchange="eHandler">
<option value="" ></option>
<option value="1" selected="selected">New York</option>
<option value="2" >Los Angeles</option>
<option value="3" >San Francisco</option>
</select>
<select name="OfficePhone" id="oPhone">
<option value="" ></option>
<option value="1">(718)555-1212</option>
<option value="2" >(213)555-1212</option>
<option value="3" >(415)555-1214</option>
</select>
You have to implement your event handler in your script, like this:
function eHandler(){
var secondSelect = document.getElementById('oPhone');
secondSelect.value = //the value you want to be selected
}

Adding/Removing/Updating options from select inputs

Here is what I've started to do: http://jsfiddle.net/nd9ny/
For now it doesn't work as I want it to.
I want to update options each time when a new select input is added or an input is removed.
For example, we have our first select input with these options:
<select>
<option value="1"></option>
<option value="2"></option>
<option value="3"></option>
<option value="4"></option>
</select>
When I add new input to my page, I want my function to update all the inputs and to remove the newly selected option from them.
<select>
<option value="1" selected></option>
<option value="3"></option> // The second one is removed
<option value="4"></option>
</select>
<select>
<option value="2" selected></option> // The first one is removed
<option value="3"></option>
<option value="4"></option>
</select>
And then, If I remove the first input, the second one becomes:
<select>
<option value="1"></option>
<option value="2" selected></option>
<option value="3"></option>
<option value="4"></option>
</select>
Pure Javascript code needed.

You may try the following solution:
- CSS:
.hidden {
display: none;
}
- JS function:
function hide_selected(el) {
var index = el.selectedIndex;
// Show every options
for(var i=0; i<el.length; i++)
el[i].className="";
// Hide the selected one
el[index].className="hidden";
}
- HTML example:
<body>
<select onchange="javascript:hide_selected(this);">
<option value="1" class="hidden" selected="selected">1</option>
<option value="2" class="">2</option>
<option value="3" class="">3</option>
<option value="4" class="">4</option>
</select>
</body>
Note: This function was tested with Firefox, you may have to check if this works with other browsers.
Hope this helps

Can't get jquery to set value of select input when value of first select changes

I'm trying to update the value of a select input when I change the value of another select input. I cannot get anything to happen on the page and want to make sure I don't have a syntax error or some other dumb thing in this code.
<div class="group">
<div class="inputs types">
<strong style="font-size:13px;">Category:</strong>
<select name="id" id="ctlJob">
<option value="1">Automotive</option>
<option value="2">Business 2 Business</option>
<option value="3">Computers</option>
<option value="4">Education</option>
<option value="5">Entertainment & The Arts</option>
<option value="6">Food & Dining</option>
<option value="7">Government & Community</option>
<option value="8">Health & Beauty</option>
<option value="9">Home & Garden</option>
<option value="10">Legal & Financial Services</option>
<option value="11">Professional Services</option>
<option value="12">Real Estate</option>
<option value="13">Recreation & Sports</option>
<option value="14">Retail Shopping</option>
<option value="15">Travel & Lodging</option>
</select>
<select name="type" id="ctlPerson"></select>
</div>
</div>
<script>
$(function() {
$("#ctlJob").change(function() {
//Get the current value of the select
var val = $(this).val();
$('#ctlPerson').html('<option value="123">ascd</option>');
});
});
</script>

Try using append instead:
$(function() {
$("#ctlJob").change(function() {
//Get the current value of the select
var val = $(this).val();
var ctl = $('#ctlPerson').append('<option value="123">'+val+'</option>')[0].options;
ctl.selectedIndex = ctl.length-1;
});
});
http://jsfiddle.net/J69q8/

I think you also need to set the 'selected' property. Add
$('#ctlPerson option[value="123"]').attr('selected', 'selected');
to the end of the script. You are currently adding the option to the select list, but are not changing the select list to show it.

<div id="test">
<select name="sel" id="sel">
<option name="1" id="1" value="1">Automotive</option>
<option name="2" id="1 value="2">Business 2 Business</option>
<option name="3" id="1 value="3">Computers</option>
</select>
<select name="sel2" id="sel2"></select>
</div>
<script>
$("#sel").change(function() {
var val = $(this).val();
$('#sel2').html('<option value="1">NEW</option>');
)};
</script>
this works fine for what you need to do.
it's something like what you have

Swap default selected select options with pure Javascript

I have a select box as follows
<select>
<option value="yes">Yes</option>
<option value="No" selected="selected">No</option>
<option value="Maybe">Maybe</option>
<option value="So">So</option>
</select>
I would like
<select>
<option value="yes">Yes</option>
<option value="No">No</option>
<option value="Maybe" selected="selected">Maybe</option>
<option value="So">So</option>
</select>
*note default selection is now "Maybe" instead of "No"
I learned jquery before really getting comfortable with pure JavaScript. So im trying to learn it.

I would assign an id to the select element:
<select id="choices">
<option value="yes">Yes</option>
<option value="No" selected="selected">No</option>
<option value="Maybe">Maybe</option>
<option value="So">So</option>
</select>
Then, access the options via the standard options array on <select> elements:
var choices = document.getElementById('choices');
choices.options[2].selected = true;

You should assign an id to the select element then do this:
var s = document.getElementById( 'select_box' );
s.options[ 2 ].selected = true;