How do I programmatically set the value of a select box element using JavaScript?

I have the following HTML <select> element:

<select id="leaveCode" name="leaveCode">
  <option value="10">Annual Leave</option>
  <option value="11">Medical Leave</option>
  <option value="14">Long Service</option>
  <option value="17">Leave Without Pay</option>
</select>

Using a JavaScript function with the leaveCode number as a parameter, how do I select the appropriate option in the list?

You can use this function:

selectElement('leaveCode', '11')

function selectElement(id, valueToSelect) {    
    let element = document.getElementById(id);
    element.value = valueToSelect;
}

Optionally if you want to trigger onchange event also, you can use :

element.dispatchEvent(new Event('change'))

If you are using jQuery you can also do this:

$('#leaveCode').val('14');

This will select the <option> with the value of 14.

---

With plain Javascript, this can also be achieved with two Document methods:

• With document.querySelector, you can select an element based on a CSS selector:

    document.querySelector('#leaveCode').value = '14'
  

• Using the more established approach with document.getElementById(), that will, as the name of the function implies, let you select an element based on its id:

    document.getElementById('leaveCode').value = '14'
  

You can run the below code snipped to see these methods and the jQuery function in action:

const jQueryFunction = () => {
  
  $('#leaveCode').val('14'); 
  
}

const querySelectorFunction = () => {
  
  document.querySelector('#leaveCode').value = '14' 
  
}

const getElementByIdFunction = () => {
  
  document.getElementById('leaveCode').value='14' 
  
}

input {
  display:block;
  margin: 10px;
  padding: 10px
}

<select id="leaveCode" name="leaveCode">
  <option value="10">Annual Leave</option>
  <option value="11">Medical Leave</option>
  <option value="14">Long Service</option>
  <option value="17">Leave Without Pay</option>
</select>

<input type="button" value="$('#leaveCode').val('14');" onclick="jQueryFunction()" />
<input type="button" value="document.querySelector('#leaveCode').value = '14'" onclick="querySelectorFunction()" />
<input type="button" value="document.getElementById('leaveCode').value = '14'" onclick="getElementByIdFunction()" />

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

function setSelectValue (id, val) {
    document.getElementById(id).value = val;
}
setSelectValue('leaveCode', 14);

Not answering the question, but you can also select by index, where i is the index of the item you wish to select:

var formObj = document.getElementById('myForm');
formObj.leaveCode[i].selected = true;

You can also loop through the items to select by display value with a loop:

for (var i = 0, len < formObj.leaveCode.length; i < len; i++) 
    if (formObj.leaveCode[i].value == 'xxx') formObj.leaveCode[i].selected = true;

I compared the different methods:

Comparison of the different ways on how to set a value of a select with JS or jQuery

code:

$(function() {
    var oldT = new Date().getTime();
     var element = document.getElementById('myId');
    element.value = 4;
    console.error(new Date().getTime() - oldT);

    oldT = new Date().getTime();
    $("#myId option").filter(function() {
        return $(this).attr('value') == 4;
    }).attr('selected', true);
    console.error(new Date().getTime() - oldT);

    oldT = new Date().getTime();
    $("#myId").val("4");
    console.error(new Date().getTime() - oldT);
});

Output on a select with ~4000 elements:

• 1 ms
• 58 ms
• 612 ms

With Firefox 10. Note: The only reason I did this test, was because jQuery performed super poorly on our list with ~2000 entries (they had longer texts between the options). We had roughly 2 s delay after a val()

Note as well: I am setting value depending on the real value, not the text value.

document.getElementById('leaveCode').value = '10';

That should set the selection to "Annual Leave"

I tried the above JavaScript/jQuery-based solutions, such as:

$("#leaveCode").val("14");

and

var leaveCode = document.querySelector('#leaveCode');
leaveCode[i].selected = true;

in an AngularJS app, where there was a required <select> element.

None of them works, because the AngularJS form validation is not fired. Although the right option was selected (and is displayed in the form), the input remained invalid (ng-pristine and ng-invalid classes still present).

To force the AngularJS validation, call jQuery change() after selecting an option:

$("#leaveCode").val("14").change();

and

var leaveCode = document.querySelector('#leaveCode');
leaveCode[i].selected = true;
$(leaveCode).change();

shortest

This is size improvement of William answer

leaveCode.value = '14';

leaveCode.value = '14';

<select id="leaveCode" name="leaveCode">
  <option value="10">Annual Leave</option>
  <option value="11">Medical Leave</option>
  <option value="14">Long Service</option>
  <option value="17">Leave Without Pay</option>
</select>

The easiest way if you need to:

1. Click a button which defines select option
   
2. Go to another page, where select option is
   
3. Have that option value selected on another page

1) your button links (say, on home page)

<a onclick="location.href='contact.php?option=1';" style="cursor:pointer;">Sales</a>
<a onclick="location.href='contact.php?option=2';" style="cursor:pointer;">IT</a>

(where contact.php is your page with select options. Note the page url has ?option=1 or 2)

2) put this code on your second page (my case contact.php)

<?
if (isset($_GET['option']) && $_GET['option'] != "") {
$pg = $_GET['option'];				
} ?>

3) make the option value selected, depending on the button clicked

<select>
<option value="Sales" <? if ($pg == '1') { echo "selected"; } ?> >Sales</option>
<option value="IT" <? if ($pg == '2') { echo "selected"; } ?> >IT</option>
</select>

.. and so on.
So this is an easy way of passing the value to another page (with select option list) through GET in url. No forms, no IDs.. just 3 steps and it works perfect.

function foo(value)
{
var e = document.getElementById('leaveCode');
if(e) e.value = value;
}

Should be something along these lines:

function setValue(inVal){
var dl = document.getElementById('leaveCode');
var el =0;
for (var i=0; i<dl.options.length; i++){
  if (dl.options[i].value == inVal){
    el=i;
    break;
  }
}
dl.selectedIndex = el;
}

Suppose your form is named form1:

function selectValue(val)
{
  var lc = document.form1.leaveCode;
  for (i=0; i<lc.length; i++)
  {
    if (lc.options[i].value == val)
    {
        lc.selectedIndex = i;
        return;
    }
  }
}

Why not add a variable for the element's Id and make it a reusable function?

function SelectElement(selectElementId, valueToSelect)
{    
    var element = document.getElementById(selectElementId);
    element.value = valueToSelect;
}

Most of the code mentioned here didn't worked for me!

At last, this worked

window.addEventListener is important, otherwise, your JS code will run before values are fetched in the Options

    window.addEventListener("load", function () {
            // Selecting Element with ID - leaveCode  //
            var formObj = document.getElementById('leaveCode');

            // Setting option as selected
            let len;
            for (let i = 0, len = formObj.length; i < len; i++){
                if (formObj[i].value == '<value to show in Select>') 
                 formObj.options[i].selected = true;
            }
    });

Hope, this helps!

You most likely want this:

$("._statusDDL").val('2');

OR

$('select').prop('selectedIndex', 3); 

If using PHP you could try something like this:

$value = '11';
$first = '';
$second = '';
$third = '';
$fourth = '';

switch($value) {
	        case '10' :
		        $first = 'selected';
			break;
	        case '11' :
		        $second = 'selected';
			break;
	        case '14' :
		        $third = 'selected';
			break;
	        case '17' :
	            $fourth = 'selected';
		    break;
		}

echo'
<select id="leaveCode" name="leaveCode">
  <option value="10" '. $first .'>Annual Leave</option>
  <option value="11" '. $second .'>Medical Leave</option>
  <option value="14" '. $third .'>Long Service</option>
  <option value="17" '. $fourth .'>Leave Without Pay</option>
</select>';

I'm afraid I'm unable to test this at the moment, but in the past, I believe I had to give each option tag an ID, and then I did something like:

document.getElementById("optionID").select();

If that doesn't work, maybe it'll get you closer to a solution :P