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JQuery get the value of the newly selected/unselected element of a select [duplicate]

I have a HTML select list, which can have multiple selects:
<select id="mySelect" name="myList" multiple="multiple" size="3">
<option value="1">First</option>
<option value="2">Second</option>
<option value="3">Third</option> `
<option value="4">Fourth</option>
...
</select>
I want to get an option's text everytime i choose it. I use jQuery to do this:
$('#mySelect').change(function() {
alert($('#mySelect option:selected').text());
});
Looks simple enough, however if select list has already some selected options - it will return their text too. As example, if i had already selected the "Second" option, after choosing "Fourth" one, alert would bring me this - "SecondFourth". So is there any short, simple way with jQuery to get only the "current" selected option's text or do i have to play with strings and filter new text?

You could do something like this, keeping the old value array and checking which new one isn't in there, like this:
var val;
$('#mySelect').change(function() {
var newVal = $(this).val();
for(var i=0; i<newVal.length; i++) {
if($.inArray(newVal[i], val) == -1)
alert($(this).find('option[value="' + newVal[i] + '"]').text());
}
val = newVal;
}); ​
Give it a try here, When you call .val() on a <select multiple> it returns an array of the values of its selected <option> elements. We're simply storing that, and when the selection changes, looping through the new values, if the new value was in the old value array ($.inArray(val, arr) == -1 if not found) then that's the new value. After that we're just using an attribute-equals selector to grab the element and get its .text().
If the value="" may contains quotes or other special characters that would interfere with the selector, use .filter() instead, like this:
$(this).children().filter(function() {
return this.value == newVal[i];
}).text());

Set a onClick on the option instead of the select:
$('#mySelect option').click(function() {
if ($(this).attr('selected')) {
alert($(this).val());
}
});

var val = ''
$('#mySelect').change(function() {
newVal = $('#mySelect option:selected').text();
val += newVal;
alert(val); # you need this.
val = newVal;
});
or let's play some more
val = '';
$('#id_timezone')
.focus(
function(){
val = $('#id_timezone option:selected').text();
})
.change(
function(){
alert(val+$('#id_timezone option:selected').text())
});
Cheers.

Remove more than 1 select option using JavaScript

I have 3 columns of HTML selection fields which need to load otions dependent on the previous selection fields.
Selection in column 2 values will be dependant on selected value in column 1 selection. I have this raw JavaScript below which add 2 selection options to a an HTML select filed and then removes 2 based on the select value in selection 1.
My problem is that the part that removes the 2 selection field options is not removing both options but instead removes 1 of them.
Demo: http://jsfiddle.net/jasondavis/croh2nj8/3/
I realize some of this uses jQuery but the goal is to use raw JS without jQuery for this part in question....
$(document).ready(function() {
$("#action").change(function() {
var el = $(this) ;
var selectAttributeEl = document.getElementById('action-attribute');
if(el.val() === "form" ) {
var option = document.createElement('option');
option.text = 'Name';
var option2 = document.createElement('option');
option2.text = 'ActionURL';
selectAttributeEl.add(option);
selectAttributeEl.add(option2);
}else if(el.val() === "link" ) {
for (var i=0; i<selectAttributeEl.length; i++){
if (selectAttributeEl.options[i].value == 'Name'){
selectAttributeEl.remove(i);
}else if(selectAttributeEl.options[i].value == 'ActionURL'){
selectAttributeEl.remove(i);
}
}
}
});
});

The problem is in the for loop where you loop through the selectobject.options. When the first if condition is true, you mutate selectobject.options by removing the Name option. On the next iteration of the loop selectobject.options[i] now returns undefined.
Let's walk through the for loop to demonstrate:
i is 0, corresponding to option ID, nothing happens.
i is 1, corresponding to option Class, nothing happens.
i is 2, corresponding to option Name, the if statement is valid and it removes the Name option. Now selectobject.options has length of 3.
i is 3, which corresponds to undefined. That is, selectobject.options[3] is undefined since the previous iteration of the loop removed an item from selectobject.options.
One possible solution, in the if and else statements you could reset i back one, with i--. Here's an updated jsFiddle. Another option is too loop through selectobject.options backwards, as mutating the latter items won't effect the counter as it moves to the former items.
There are other ways to correct this as well, like creating a new options array based on the values you want to keep in the options, then loading it the new options into the select.

As I stated, you're getting the issue, very simply, because the for loop is started from index 0 and working your way up. When you remove an element, you remove it from the NodeList of options. Easiest way I know of is to start from the end of the node list and work your way to node number 0.
$(document).ready(function() {
$("#action").change(function() {
var el = $(this);
if (el.val() === "form") {
//$("#action-attribute").append(' <option value="Name">Name</option>');
//$("#action-attribute").append(' <option value="ActionURL">ActionURL</option>');
var x = document.getElementById('action-attribute');
var option = document.createElement('option');
option.text = 'Name';
var option2 = document.createElement('option');
option2.text = 'ActionURL';
x.add(option);
x.add(option2);
} else if (el.val() === "link") {
//$("#action-attribute option:last-child").remove() ;
var selectobject = document.getElementById("action-attribute");
var remove_array = ['Name', 'ActionURL'];
for (var i = selectobject.options.length - 1; i >= 0; i--) {
if (remove_array.indexOf(selectobject.options[i].value) != -1) {
selectobject.removeChild(selectobject.options[i]);
}
}
}
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
When :
<select id="action" name="action">
<option value="link">Link Clicked</option>
<option value="form">Form Submitted</option>
</select>
with:
<select id="action-attribute" name="action-attribute">
<option>ID</option>
<option>Class</option>
</select>

May I propose a different approach? Instead of maintaining the state of the menu by removing elements that shouldn't be there, blow away the menu option tags entirely and replace.
$(document).ready(function() {
var options = {
link: ['ID', 'Class']
},
dependentMenu = document.getElementById('action-attribute');
options.form = options.link.concat(['Name', 'ActionURL']);
$("#action").change(function() {
var el = $(this);
while (dependentMenu.firstChild) {
dependentMenu.removeChild(dependentMenu.firstChild);
}
options[el.val()].forEach(function(value) {
var option = document.createElement('option');
option.text = value;
dependentMenu.add(option);
});
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
When :
<select id="action" name="action">
<option value="link">Link Clicked</option>
<option value="form">Form Submitted</option>
</select>
with:
<select id="action-attribute" name="action-attribute">
<option>ID</option>
<option>Class</option>
</select>

Javascript: select.options doesn't work properly

I am using this code, to iterate through the Options of a Select and mark the option with value 1 as selected, but it doesn't work properly, giving me the error
"Cannot read property '0' of undefined"
What's the problem here? Might be of importance: If i use $('#Select').length it works, however, all tutorials i've found work the other way, and i have no idea how to access the options any other way.
for (var i = 0; i < $('#Select').options.length; i++) {
if ($(this).options[i].value == 1)
$(this).selectedIndex = i;
}

There are several issues here.
First you can't write $('#Select').options.length, which has no sense. To get the number of <option> elements in the #Select (which is likely a <select> element), you can do $('#Select option').length.
Anyway since you want to
mark the option with value 1 as selected
you don't need to iterate and can simply use:
$('#Select option[value=1]').attr('selected','selected');

Try this:
$('#Select option[value="1"]').attr("selected", "selected");

You are trying to use native Dom attributes with jQuery objects. here is a way to do the same with just javascript.
var select = document.querySelector('#select');
selectByValue( select, '1' );
function selectByValue( select, value ){
// use array prototype to filter down to a single value
var option = Array.prototype.filter.call( select, function( option ){
option.removeAttribute('selected');
return option.value == value;
})
console.log( option[0] );
// if there is an option that matches set it's selected attribute
option[0] && option[0].setAttribute('selected', 'selected');
}
<script src="http://codepen.io/synthet1c/pen/WrQapG.js"></script>
<select id="select">
<option value="0" id="option_zero">zero</option>
<option value="1" id="option_one">one</option>
<option value="2" id="option_two">two</option>
</select>

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

Search a dropdown

I have this HTML dropdown:
<form>
<input type="text" id="realtxt" onkeyup="searchSel()">
<select id="select" name="basic-combo" size="1">
<option value="2821">Something </option>
<option value="2825"> Something </option>
<option value="2842"> Something </option>
<option value="2843"> _Something </option>
<option value="15999"> _Something </option>
</select>
</form>
I need to search trough it using javascript.
This is what I have now:
function searchSel() {
var input=document.getElementById('realtxt').value.toLowerCase();
var output=document.getElementById('basic-combo').options;
for(var i=0;i<output.length;i++) {
var outputvalue = output[i].value;
var output = outputvalue.replace(/^(\s| )+|(\s| )+$/g,"");
if(output.indexOf(input)==0){
output[i].selected=true;
}
if(document.forms[0].realtxt.value==''){
output[0].selected=true;
}
}
}
The code doesn't work, and it's probably not the best.
Can anyone show me how I can search trough the dropdown items and when i hit enter find the one i want, and if i hit enter again give me the next result, using plain javascript?

Here's the fixed code. It searches for the first occurrence only:
function searchSel() {
var input = document.getElementById('realtxt').value;
var list = document.getElementById('select');
var listItems = list.options;
if(input === '')
{
listItems[0].selected = true;
return;
}
for(var i=0;i<list.length;i++) {
var val = list[i].value.toLowerCase();
if(val.indexOf(input) == 0) {
list.selectedIndex = i;
return;
}
}
}
You should not check for empty text outside the for loop.
Also, this code will do partial match i.e. if you type 'A', it will select the option 'Artikkelarkiv' option.

Right of the bat, your code won't work as you're selecting the dropdown wrong:
document.getElementById("basic-combo")
is wrong, as the id is select, while "basic-combo" is the name attribute.
And another thing to note, is that you have two variable named output. Even though they're in different scopes, it might become confusing.

For stuff like this, I'd suggest you use a JavaScript library like jQuery (http://jquery.com) to make DOM interaction easier and cross-browser compatible.
Then, you can select and traverse all the elements from your select like this:
$("#select").each(function() {
var $this = $(this); // Just a shortcut
var value = $this.val(); // The value of the option element
var content = $this.html(); // The text content of the option element
// Process as you wish
});