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How to change to default the selected dropdown [duplicate]

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:
function selectElement(id, valueToSelect) {
let element = document.getElementById(id);
element.value = valueToSelect;
}
selectElement('leaveCode', '11');
<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>
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();

Short
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;
}

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;
}
}
}

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;
}

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

Dynamically adding a new option value to a selectbox if it isn't already in there

I have a small bit of a delema.
I have the following static select box below, however, the database will compare its cell value to that of the select box and select it.
My question to you is how can I design a function that would dynamically add a new select option (at the end of the existing list) if it already isn't in the list?
This doesn't seem to be working for me?
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function test() {
//document.getElementById('name').innerHTML = "test"
document.getElementById('name').text = "test"
}
</script>
</head>
<body>
<select id="name">
<option value=""></option>
<option value="John">John</option>
<option value="Patrick">Patrick</option>
<option value="Jean">Jean</option>
<option value="Jackie">Jackie</option>
<option value="Stephanie">Stephanie</option>
<option value="Nicole">Nicole</option>
<option value="Lucie">Lucie</option>
</select>
<input id="btn1" type="button" value="testme" onclick="test()" />
</body>
</html>

You'll have to check each one:
function test() {
var checkWhat = 'test'; // value to check for
var options = document.getElementById('name').getElementsByTagName('option'),
exists = false;
for (var i=options.length; i--;) {
if ( options[i].value == checkWhat ) {
exists = true; // an option with that value already exists
break;
}
}
if (!exists) {
var option = document.createElement('option');
option.value = 'test';
option.innerHTML = 'test';
document.getElementById('name').appendChild(option);
}
}

You could create a function which loops through all the options in the select element and if the option value doesn't already exist, append it to the select tag.
var addOption = function(value){
var select = document.getElementById('name'), // get the select tag
options = select.getElementsByTagName('option'), // get all option tags within that select
alreadyExists = false;
for(var i = 0, l = options.length; i < l; i++){ // loop through the existing options
if(options[i].value == value) // check if value already exists
alreadyExists = true;
}
if(!alreadyExists){ // if value doesn't already exist
var newOption = document.createElement('option');// create a new option and add it to the select
newOption.value = value;
newOption.innerHTML = value;
select.appendChild(newOption);
}
};
Demo: http://jsfiddle.net/2TZ45/

How to change options of a select using JavaScript

I have an HTML page in which I have 2 selects.
<select id="field" name="field" onchange="checkValidOption();">
<option />
<option value="Plugin ID">Plugin ID</option>
<option value="Name">Name</option>
</select>
<select id="operator" name="operator" onchange="checkValidOption();">
<option />
<option value="EQUALS">EQUALS</option>
<option value="CONTAINS">CONTAINS</option>
<option value="NOT CONTAINS">NOT CONTAINS</option>
<option value="REGEX">REGEX</option>
</select>
What I'd like to happen is that checkValidOption() could make it so that if "Plugin ID" is selected in field that the only option is EQUALS (and it's selected) and otherwise all the other options are available. Any idea on how to approach this?
I tried changing the innerHTML of the operator select in JS:
document.getElementById("operator").innerHTML =
"<option value='EQUALS'>EQUALS</option>";
However this results in an empty select (this would also include manually setting the many options for going back to having all the ones listed above).
I can't think of another solution, any help would be greatly appreciated.

Try this:
Demo here
var field = document.getElementById('field');
var operator = document.getElementById('operator');
field.onchange = function () { fieldcheck(); }
operator.onchange = function () { fieldcheck(); }
fieldcheck();
function fieldcheck() {
if (field.value == 'Plugin ID') {
for (i = 0; i < operator.options.length; ++i) {
if (operator.options[i].value != 'EQUALS') {
operator.options[i].disabled = true;
}
};
operator.value = 'EQUALS';
} else {
for (i = 0; i < operator.options.length; ++i) {
operator.options[i].disabled = false;
};
}
}

To manipulate options when Plugin ID was selected:
function checkValidOption(){
var x=document.getElementById("field");
var y=document.getElementById("operator");
if (x.options[1].selected === true){
document.getElementById("operator").options[1].selected = true;
for(var i=0; i<y.length; i++){
if (i !== 1){
//disabling the other options
document.getElementById("operator").options[i].disabled = true;
}
}
}
else{
for(var i=0; i<y.length; i++){
//enabling the other options
document.getElementById("operator").options[i].disabled = false;
}
}
}
Here's a link to fiddle

A select field doesn't use the innerHTML method, you need to use value.
document.getElementById("operator").value = "...";

heres a jquery solution.
every time the first select changes, it produces new options from an array for the 2nd select. issue here is i had to change the option values of the first select to 0 and 1 to select which value in the array, you can manipulate those later if you are storing this info somewhere
http://jsfiddle.net/2TZJh/
$(document).ready(function() {
$("#field").change(function() {
var val = $(this).val();
$("#operator").html(options[val]);
});
var options = [
'<option value="EQUALS">EQUALS</option>',
'<option></option><option value="EQUALS">EQUALS</option><option value="CONTAINS">CONTAINS</option> <option value="NOT CONTAINS">NOT CONTAINS</option> <option value="REGEX">REGEX</option>'
];
});

How to set selectedIndex of select element using display text?

How to set selectedIndex of select element using display text as reference?
Example:
<input id="AnimalToFind" type="text" />
<select id="Animals">
<option value="0">Chicken</option>
<option value="1">Crocodile</option>
<option value="2">Monkey</option>
</select>
<input type="button" onclick="SelectAnimal()" />
<script type="text/javascript">
function SelectAnimal()
{
//Set selected option of Animals based on AnimalToFind value...
}
</script>
Is there any other way to do this without a loop? You know, I'm thinking of a built-in JavaScript code or something. Also, I don't use jQuery...

Try this:
function SelectAnimal() {
var sel = document.getElementById('Animals');
var val = document.getElementById('AnimalToFind').value;
for(var i = 0, j = sel.options.length; i < j; ++i) {
if(sel.options[i].innerHTML === val) {
sel.selectedIndex = i;
break;
}
}
}

<script type="text/javascript">
function SelectAnimal(){
//Set selected option of Animals based on AnimalToFind value...
var animalTofind = document.getElementById('AnimalToFind');
var selection = document.getElementById('Animals');
// select element
for(var i=0;i<selection.options.length;i++){
if (selection.options[i].innerHTML == animalTofind.value) {
selection.selectedIndex = i;
break;
}
}
}
</script>
setting the selectedIndex property of the select tag will choose the correct item. it is a good idea of instead of comparing the two values (options innerHTML && animal value) you can use the indexOf() method or regular expression to select the correct option despite casing or presense of spaces
selection.options[i].innerHTML.indexOf(animalTofind.value) != -1;
or using .match(/regular expression/)

If you want this without loops or jquery you could use the following
This is straight up JavaScript. This works for current web browsers. Given the age of the question I am not sure if this would have worked back in 2011. Please note that using css style selectors is extremely powerful and can help shorten a lot of code.
// Please note that querySelectorAll will return a match for
// for the term...if there is more than one then you will
// have to loop through the returned object
var selectAnimal = function() {
var animals = document.getElementById('animal');
if (animals) {
var x = animals.querySelectorAll('option[value="frog"]');
if (x.length === 1) {
console.log(x[0].index);
animals.selectedIndex = x[0].index;
}
}
}
<html>
<head>
<title>Test without loop or jquery</title>
</head>
<body>
<label>Animal to select
<select id='animal'>
<option value='nothing'></option>
<option value='dog'>dog</option>
<option value='cat'>cat</option>
<option value='mouse'>mouse</option>
<option value='rat'>rat</option>
<option value='frog'>frog</option>
<option value='horse'>horse</option>
</select>
</label>
<button onclick="selectAnimal()">Click to select animal</button>
</body>
</html>
document.getElementById('Animal').querySelectorAll('option[value="searchterm"]');
in the index object you can now do the following:
x[0].index

Try this:
function SelectAnimal()
{
var animals = document.getElementById('Animals');
var animalsToFind = document.getElementById('AnimalToFind');
// get the options length
var len = animals.options.length;
for(i = 0; i < len; i++)
{
// check the current option's text if it's the same with the input box
if (animals.options[i].innerHTML == animalsToFind.value)
{
animals.selectedIndex = i;
break;
}
}
}

You can set the index by this code :
sel.selectedIndex = 0;
but remember a caution in this practice, You would not be able to call the server side onclick method if you select the previous value selected in the drop down..

Add name attribute to your option:
<option value="0" name="Chicken">Chicken</option>
With that you can use the HTMLOptionsCollection.namedItem("Chicken").value to set the value of your select element.

You can use the HTMLOptionsCollection.namedItem()
That means that you have to define your select options to have a name attribute and have the value of the displayed text.
e.g
California

How to get the value of a multiple option dropdown?

Say I have this dropdown:
<select name="color" multiple="multiple">
<option value="red">Red</option>
<option value="green">Green</option>
<option value="blue">Blue</option>
</select>
So basically more than 1 color can be selected. What I'd like is that if a user selects red, and then clicks green, i'd like a function to be called each time which pops up a message box saying the color which was most recently clicked.
I've tried this:
<option value="red" onclick="alert('red');">Red</option>
<option value="green" onclick="alert('green');">Green</option>
<option value="blue" onclick="alert('blue');">Blue</option>
This works in firefox and chrome, but not in IE.
Any ideas?

$("select[name='color']").change(function() {
// multipleValues will be an array
var multipleValues = $(this).val() || [];
// Alert the list of values
alert(multipleValues[multipleValues.length - 1]);
});
Here's another examples: http://api.jquery.com/val/

The following code should do what I think you're after. Each time an item is selected, it compares the current list of selections against the previous list, and works out which items have changed:
<html>
<head>
<script type="text/javascript">
function getselected(selectobject) {
var results = {};
for (var i=0; i<selectobject.options.length; i++) {
var option = selectobject.options[i];
var value = option.value;
results[value] = option.selected;
}
return results;
}
var currentselect = {};
function change () {
var selectobject = document.getElementById("colorchooser");
var newselect = getselected(selectobject);
for (var k in newselect) {
if (currentselect[k] != newselect[k]) {
if (newselect[k]) {
alert("Option " + k + " selected");
} else {
alert("Option " + k + " deselected");
}
}
}
currentselect = newselect;
}
</script>
</head>
<body>
<select id="colorchooser"
name="color"
multiple="multiple"
onchange='javascript:change();'
>
<option value="red">Red</option>
<option value="green">Green</option>
<option value="blue">Blue</option>
</select>
</body>
</html>
It should work just as well in Internet Explorer as Firefox et al.

Since you using jQuery,I suggest you to take a look at this superb plugins. This plugins will transform a multiple select dropdown into a checkbox list, so user can select multiple values with easy.
To get the values, I suggest you use fieldValue methods from jQuery form plugins. It's a robust way to get value from any type of form element. Beside, you can use this plugins to submit your form via AJAX easily.

This will alert only the last (most recent) selected value. Calling $(this).val() using the select's change handler will return an array of all your selected values:
$(document).ready(function() {
$("select[name=color] option").click(function() {
alert($(this).val());
});
});

I am not sure what you exactly want. This will always alert the last selected color:
$(function(){
var selected = Array();
$('select[name=color] option').click(function() {
if($(this).is(':selected')) {
selected.push($(this).val());
}
else {
for(var i = 0; i < selected.length;i++) {
if(selected[i] == $(this).val()) {
selected = selected.splice(i,1);
}
}
}
alert(selected[selected.length -1])
});
});
The array is used to maintain the history of selected colors.
For the last clicked color, it is simpler:
$(function(){
$('select[name=color] option').click(function() {
alert($(this).val());
});
});

This is so complicated to accomplish that I used a simpler option of listing the items with a checkbox next to them and a select/unselect all button. That works much better and is also supported by IE. Thanks to everyone for their answers.