I have an input form that lets me select from multiple options, and do something when the user changes the selection. Eg,
<select onChange="javascript:doSomething();">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
Now, doSomething() only gets triggered when the selection changes.
I want to trigger doSomething() when the user selects any option, possibly the same one again.
I have tried using an "onClick" handler, but that gets triggered before the user starts the selection process.
So, is there a way to trigger a function on every select by the user?
Update:
The answer suggested by Darryl seemed to work, but it doesn't work consistently. Sometimes the event gets triggered as soon as user clicks the drop-down menu, even before the user has finished the selection process!
I needed something exactly the same. This is what worked for me:
<select onchange="doSomething();" onfocus="this.selectedIndex = -1;">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
Supports this:
when the user selects any option, possibly the same one again
Here is the simplest way:
<select name="ab" onchange="if (this.selectedIndex) doSomething();">
<option value="-1">--</option>
<option value="1">option 1</option>
<option value="2">option 2</option>
<option value="3">option 3</option>
</select>
Works both with mouse selection and keyboard Up/Down keys whes select is focused.
I had the same problem when I was creating a design a few months back. The solution I found was to use .live("change", function()) in combination with .blur() on the element you are using.
If you wish to have it do something when the user simply clicks, instead of changing, just replace change with click.
I assigned my dropdown an ID, selected, and used the following:
$(function () {
$("#selected").live("change", function () {
// do whatever you need to do
// you want the element to lose focus immediately
// this is key to get this working.
$('#selected').blur();
});
});
I saw this one didn't have a selected answer, so I figured I'd give my input. This worked excellently for me, so hopefully someone else can use this code when they get stuck.
http://api.jquery.com/live/
Edit: Use the on selector as opposed to .live. See jQuery .on()
Just an idea, but is it possible to put an onclick on each of the <option> elements?
<select>
<option onclick="doSomething(this);">A</option>
<option onclick="doSomething(this);">B</option>
<option onclick="doSomething(this);">C</option>
</select>
Another option could be to use onblur on the select. This will fire anytime the user clicks away from the select. At this point you could determine what option was selected. To have this even trigger at the correct time, the onclick of the option's could blur the field (make something else active or just .blur() in jQuery).
If you really need this to work like this, I would do this (to ensure it works by keyboard and mouse)
Add an onfocus event handler to the select to set the "current" value
Add an onclick event handler to the select to handle mouse changes
Add an onkeypress event handler to the select to handle keyboard changes
Unfortunately the onclick will run multiple times (e.g. on onpening the select... and on selection/close) and the onkeypress may fire when nothing changes...
<script>
function setInitial(obj){
obj._initValue = obj.value;
}
function doSomething(obj){
//if you want to verify a change took place...
if(obj._initValue == obj.value){
//do nothing, no actual change occurred...
//or in your case if you want to make a minor update
doMinorUpdate();
} else {
//change happened
getNewData(obj.value);
}
}
</script>
<select onfocus="setInitial(this);" onclick="doSomething();" onkeypress="doSomething();">
...
</select>
The onclick approach is not entirely bad but as said, it will not be triggered when the value isn't changed by a mouse-click.
It is however possible to trigger the onclick event in the onchange event.
<select onchange="{doSomething(...);if(this.options[this.selectedIndex].onclick != null){this.options[this.selectedIndex].onclick(this);}}">
<option onclick="doSomethingElse(...);" value="A">A</option>
<option onclick="doSomethingElse(..);" value="B">B</option>
<option onclick="doSomethingElse(..);" value="Foo">C</option>
</select>
I know this question is very old now, but for anyone still running into this problem, I have achieved this with my own website by adding an onInput event to my option tag, then in that called function, retrieving the value of that option input.
<select id='dropdown' onInput='myFunction()'>
<option value='1'>1</option>
<option value='2'>2</option>
</select>
<p>Output: </p>
<span id='output'></span>
<script type='text/javascript'>
function myFunction() {
var optionValue = document.getElementById("dropdown").value;
document.getElementById("output").innerHTML = optionValue;
}
</script>
Going to expand on jitbit's answer. I found it weird when you clicked the drop down and then clicked off the drop down without selecting anything. Ended up with something along the lines of:
var lastSelectedOption = null;
DDChange = function(Dd) {
//Blur after change so that clicking again without
//losing focus re-triggers onfocus.
Dd.blur();
//The rest is whatever you want in the change.
var tcs = $("span.on_change_times");
tcs.html(+tcs.html() + 1);
$("span.selected_index").html(Dd.prop("selectedIndex"));
return false;
};
DDFocus = function(Dd) {
lastSelectedOption = Dd.prop("selectedIndex");
Dd.prop("selectedIndex", -1);
$("span.selected_index").html(Dd.prop("selectedIndex"));
return false;
};
//On blur, set it back to the value before they clicked
//away without selecting an option.
//
//This is what is typically weird for the user since they
//might click on the dropdown to look at other options,
//realize they didn't what to change anything, and
//click off the dropdown.
DDBlur = function(Dd) {
if (Dd.prop("selectedIndex") === -1)
Dd.prop("selectedIndex", lastSelectedOption);
$("span.selected_index").html(Dd.prop("selectedIndex"));
return false;
};
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id="Dd" onchange="DDChange($(this));" onfocus="DDFocus($(this));" onblur="DDBlur($(this));">
<option>1</option>
<option>2</option>
</select>
<br/>
<br/>Selected index: <span class="selected_index"></span>
<br/>Times onchange triggered: <span class="on_change_times">0</span>
This makes a little more sense for the user and allows JavaScript to run every time they select any option including an earlier option.
The downside to this approach is that it breaks the ability to tab onto a drop down and use the arrow keys to select the value. This was acceptable for me since all the users click everything all the time until the end of eternity.
To properly fire an event every time the user selects something(even the same option), you just need to trick the select box.
Like others have said, specify a negative selectedIndex on focus to force the change event. While this does allow you to trick the select box, it won't work after that as long as it still has focus. The simple fix is to force the select box to blur, shown below.
Standard JS/HTML:
<select onchange="myCallback();" onfocus="this.selectedIndex=-1;this.blur();">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
jQuery Plugin:
<select>
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<script type="text/javascript">
$.fn.alwaysChange = function(callback) {
return this.each(function(){
var elem = this;
var $this = $(this);
$this.change(function(){
if(callback) callback($this.val());
}).focus(function(){
elem.selectedIndex = -1;
elem.blur();
});
});
}
$('select').alwaysChange(function(val){
// Optional change event callback,
// shorthand for $('select').alwaysChange().change(function(){});
});
</script>
You can see a working demo here.
first of all u use onChange as an event handler and then use flag variable to make it do the function u want every time u make a change
<select
var list = document.getElementById("list");
var flag = true ;
list.onchange = function () {
if(flag){
document.bgColor ="red";
flag = false;
}else{
document.bgColor ="green";
flag = true;
}
}
<select id="list">
<option>op1</option>
<option>op2</option>
<option>op3</option>
</select>
This may not directly answer your question, but this problem could be solved by simple design level adjustments. I understand this may not be 100% applicable to all use-cases, but I strongly urge you to consider re-thinking your user flow of your application and if the following design suggestion can be implemented.
I decided to do something simple than hacking alternatives for onChange() using other events that were not really meant for this purpose (blur, click, etc.)
The way I solved it:
Simply pre-pend a placeholder option tag such as select that has no value to it.
So, instead of just using the following structure, which requires hack-y alternatives:
<select>
<option>A</option>
<option>B</option>
<option>C</option>
</select>
Consider using this:
<select>
<option selected="selected">Select...</option>
<option>A</option>
<option>B</option>
<option>C</option>
</select>
So, this way, your code is a LOT more simplified and the onChange will work as expected, every time the user decides to select something other than the default value. You could even add the disabled attribute to the first option if you don't want them to select it again and force them to select something from the options, thus triggering an onChange() fire.
At the time of this answer, I'm writing a complex Vue application and I found that this design choice has simplified my code a lot. I spent hours on this problem before I settled down with this solution and I didn't have to re-write a lot of my code. However, if I went with the hacky alternatives, I would have needed to account for the edge cases, to prevent double firing of ajax requests, etc. This also doesn't mess up the default browser behaviour as a nice bonus (tested on mobile browsers as well).
Sometimes, you just need to take a step back and think about the big picture for the simplest solution.
Add an extra option as the first, like the header of a column, which will be the default value of the dropdown button before click it and reset at the end of doSomething(), so when choose A/B/C, the onchange event always trigs, when the selection is State, do nothing and return. onclick is very unstable as many people mentioned before. So all we need to do is to make an initial button label which is different as your true options so the onchange will work on any option.
<select id="btnState" onchange="doSomething(this)">
<option value="State" selected="selected">State</option>
<option value="A">A</option>
<option value="B">B</option>
<option value="C">C</option>
</select>
function doSomething(obj)
{
var btnValue = obj.options[obj.selectedIndex].value;
if (btnValue == "State")
{
//do nothing
return;
}
// Do your thing here
// reset
obj.selectedIndex = 0;
}
Actually, the onclick events will NOT fire when the user uses the keyboard to change the selection in the select control. You might have to use a combination of onChange and onClick to get the behavior you're looking for.
The wonderful thing about the select tag (in this scenario) is that it will grab its value from the option tags.
Try:
<select onChange="javascript:doSomething(this.value);">
<option value="A">A</option>
<option value="B">B</option>
<option value="Foo">C</option>
</select>
Worked decent for me.
What I did when faced with a similar Problem is I added an 'onFocus' to the select box which appends a new generic option ('select an option'or something similar) and default it as the selected option.
So my goal was to be able to select the same value multiple times which essentially overwrites the the onchange() function and turn it into a useful onclick() method.
Based on the suggestions above I came up with this which works for me.
<select name="ab" id="hi" onchange="if (typeof(this.selectedIndex) != undefined) {alert($('#hi').val()); this.blur();}" onfocus="this.selectedIndex = -1;">
<option value="-1">--</option>
<option value="1">option 1</option>
<option value="2">option 2</option>
<option value="3">option 3</option>
</select>
http://jsfiddle.net/dR9tH/19/
2022 VANILLA JAVASCRIPT
...because this is a top hit on Google.
Original Poster did NOT ask for a JQuery solution, yet all answers ONLY demonstrate JQuery or inline SELECT tag event.
Use an event listener with the 'change' event.
const selectDropdown = document.querySelector('select');
selectDropdown.addEventListener('change', function (e) { /* your code */ });
... or call a seperate function:
function yourFunc(e) { /* your code here */ }
const selectDropdown = document.querySelector('select');
selectDropdown.addEventListener('change', yourFunc);
Kindly note that Event Handlers are not supported for the OPTION tag on IE, with a quick thinking..I came up with this solution, try it and give me your feedback:
<script>
var flag = true;
function resetIndex(selObj) {
if(flag) selObj.selectedIndex = -1;
flag = true;
}
function doSomething(selObj) {
alert(selObj.value)
flag = false;
}
</script>
<select onchange="doSomething(this)" onclick="resetIndex(this)">
<option value="A">A</option>
<option value="B">B</option>
<option value="C">C</option>
</select>
What I'm doing here actually is resetting the select index so that the onchange event will be triggered always, true that you we lose the selected item when you click and it maybe annoying if your list is long, but it may help you in someway..
use jquery:
<select class="target">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<script>
$('.target').change(function() { doSomething(); });
</script>
Here's my solution, completely different to any else on here. It uses the mouse position to figure out if an option was clicked as oppose to clicking on the select box to open the dropdown. It makes use of the event.screenY position as this is the only reliable cross browser variable. A hover event has to be attached first so it can figure out the controls position relative to the screen before the click event.
var select = $("select");
var screenDif = 0;
select.bind("hover", function (e) {
screenDif = e.screenY - e.clientY;
});
select.bind("click", function (e) {
var element = $(e.target);
var eventHorizon = screenDif + element.offset().top + element.height() - $(window).scrollTop();
if (e.screenY > eventHorizon)
alert("option clicked");
});
Here is my jsFiddle
http://jsfiddle.net/sU7EV/4/
you should try using option:selected
$("select option:selected").click(doSomething);
What works for me:
<select id='myID' onchange='doSomething();'>
<option value='0' selected> Select Option </option>
<option value='1' onclick='if (!document.getElementById("myID").onchange()) doSomething();' > A </option>
<option value='2' onclick='if (!document.getElementById("myID").onchange()) doSomething();' > B </option>
</select>
In that way, onchange calls 'doSomething()' when the option changes, and
onclick calls 'doSomething()' when onchange event is false, in other words, when you select the same option
Try this (event triggered exactly when you select option, without option changing):
$("select").mouseup(function() {
var open = $(this).data("isopen");
if(open) {
alert('selected');
}
$(this).data("isopen", !open);
});
http://jsbin.com/dowoloka/4
The one True answer is to not use the select field (if you need to do something when you re-select same answer.)
Create a dropdown menu with conventional div, button, show/hide menu. Link: https://www.w3schools.com/howto/howto_js_dropdown.asp
Could have been avoided had one been able to add event listeners to options. If there had been an onSelect listener for select element. And if clicking on the select field didn't aggravatingly fire off mousedown, mouseup, and click all at the same time on mousedown.
<script>
function abc(selectedguy) {
alert(selectedguy);
}
</script>
<select onchange="abc(this.selectedIndex);">
<option>option one</option>
<option>option two</option>
</select>
Here you have the index returned, and in the js code you can use this return with one switch or anything you want.
Try this:
<select id="nameSelect" onfocus="javascript:document.getElementById('nameSelect').selectedIndex=-1;" onchange="doSomething(this);">
<option value="A">A</option>
<option value="B">B</option>
<option value="C">C</option>
</select>
A long while ago now but in reply to the original question, would this help ?
Just put onClick into the SELECT line.
Then put what you want each OPTION to do in the OPTION lines.
ie:
<SELECT name="your name" onClick>
<option value ="Kilometres" onClick="YourFunction()">Kilometres
-------
-------
</SELECT>
<select name="test[]"
onchange="if(this.selectedIndex < 1){this.options[this.selectedIndex].selected = !1}">
<option>1</option>
<option>2</option>
<option>3</option>
</select>
I had faced a similar need and ended up writing a angularjs directive for the same -
guthub link - angular select
Used element[0].blur(); to remove the focus off the select tag. Logic is to trigger this blur on second click of the dropdown.
as-select gets triggered even when user selects the same value in the dropdown.
DEMO - link
There are a few things you want to do here to make sure it remembers older values and triggers an onchange event even if the same option is selected again.
The first thing you want is a regular onChange event:
$("#selectbox").on("change", function(){
console.log($(this).val());
doSomething();
});
To have the onChange event trigger even when the same option is selected again, you can unset selected option when the dropdown receives focus by setting it to an invalid value. But you also want to store the previously selected value to restore it in case the user does not select any new option:
prev_select_option = ""; //some kind of global var
$("#selectbox").on("focus", function(){
prev_select_option = $(this).val(); //store currently selected value
$(this).val("unknown"); //set to an invalid value
});
The above code will allow you to trigger onchange even if the same value is selected. However, if the user clicks outside the select box, you want to restore the previous value. We do it on onBlur:
$("#selectbox").on("blur", function(){
if ($(this).val() == null) {
//because we previously set an invalid value
//and user did not select any option
$(this).val(prev_select_option);
}
});
This question already has answers here:
Get selected value of a dropdown's item using jQuery
(31 answers)
Closed 7 years ago.
I have a dropdown menu of values:
<select class="notifications-dropdown">
<option value="val1">Val4</option>
<option value="val2">Val3</option>
<option value="val3">Val2</option>
<option value="val4">Val1</option>
</select>
I want to make it so when a user selects one of the options from the dropdown, that option has a 'selected' attribute toggled on. For example, if a user clicks the dropdown and selects Val3 then the DOM should change as follows:
<select class="notifications-dropdown">
<option value="val1">Val4</option>
<option value="val2" selected>Val3</option>
<option value="val3">Val2</option>
<option value="val4">Val1</option>
</select>
I am not sure what jQuery event to listen for to know when a user selects an option though. I tried listening for a change event on the .notifications-dropdown but the generated event object does not give me any indication about which option was selected. How can I determine what option is selected on a dropdown?
Just use .val() on your select list.
$('.notifications-dropdown').change(function() {
alert($(this).val());
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select class="notifications-dropdown">
<option value="val1">Val4</option>
<option value="val2">Val3</option>
<option value="val3">Val2</option>
<option value="val4">Val1</option>
</select>
this when used inside of a jQuery callback is the element which the event occurred on.
You seem to be on the right track with the change event. But that is the thing, the change event just tells you that the field/option selected has changed, it, and any other event listener, will not provide a value.
To get the value, you will need to reference jQuery like so:
$('.notifications-dropdown option:selected').text();
or to get the value of the option selected, you can reference it like so:
$('.notifications-dropdown option:selected').val();
You were on the right track:
// on Dom-ready
$(function() {
// bind the 'change' event
$('.notifications-dropdown').change(function() {
// $(this).val() will have the selected value
alert($(this).val());
}).change(); // fire it once on page-load if you need to do anything based on the current value
});
The user's action of selecting a new option will modify the DOM element's selected attribute -- you don't need to do that programmatically.
Use below code on a jquery change event. Assume, select tag has id="selectId"
To Read Select Option Value
$('#selectId').val();
To Set Select Option Value
$('#selectId').val('newValue');
To Read Selected Text
$('#selectId>option:selected').text();
Use .val() method
Get the current value of the first element in the set of matched elements or set the value of every matched element.
The .val() method is primarily used to get the values of form elements such as input, select and textarea.
$('.notifications-dropdown').change(function() {
alert($(this).val());
});
What would be the best way to reset the selected item to default? I'm using Select2 library and when using a normal button type="reset", the value in the dropdown doesn't reset.
So when I press my button I want "All" to be shown again.
jQuery
$("#d").select2();
html
<select id="d" name="d">
<option selected disabled>All</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
I'd try something like this:
$(function(){
$("#searchclear").click(function(){
$("#d").select2('val', 'All');
});
});
You can also reset select2 value using
$(function() {
$('#d').select2('data', null)
})
alternately you can pass 'allowClear': true when calling select2 and it will have an X button to reset its value.
version 4.0
$('#d').val('').trigger('change');
This is the correct solution from now on according to deprecated message thrown in debug mode:
"The select2("val") method has been deprecated and will be removed in later Select2 versions. Use $element.val() instead"
According to the latest version (select2 3.4.5) documented here, it would be as simple as:
$("#my_select").select2("val", "");
you can used:
$("#d").val(null).trigger("change");
It's very simple and work right!
If use with reset button:
$('#btnReset').click(function() {
$("#d").val(null).trigger("change");
});
The best way of doing it is:
$('#e1.select2-offscreen').empty(); //#e1 : select 2 ID
$('#e1').append(new Option()); // to add the placeholder and the allow clear
I see three issues:
The display of the Select2 control is not refreshed when its value is changed due to a form reset.
The "All" option does not have a value attribute.
The "All" option is disabled.
First, I recommend that you use the setTimeout function to ensure that code is executed after the form reset is complete.
You could execute code when the button is clicked:
$('#searchclear').click(function() {
setTimeout(function() {
// Code goes here.
}, 0);
});
Or when the form is reset:
$('form').on('reset', function() {
setTimeout(function() {
// Code goes here.
}, 0);
});
As for what code to use:
Since the "All" option is disabled, the form reset does not make it the selected value. Therefore, you must explicitly set it to be the selected value. The way to do that is with the Select2 "val" function. And since the "All" option does not have a value attribute, its value is the same as its text, which is "All". Therefore, you should use the code given by thtsigma in the selected answer:
$("#d").select2('val', 'All');
If the attribute value="" were to be added to the "All" option, then you could use the code given by Daniel Dener:
$("#d").select2('val', '');
If the "All" option was not disabled, then you would just have to force the Select2 to refresh, in which case you could use:
$('#d').change();
Note: The following code by Lenart is a way to clear the selection, but it does not cause the "All" option to be selected:
$('#d').select2('data', null)
If you have a populated select widget, for example:
<select>
<option value="1">one</option>
<option value="2" selected="selected">two</option>
<option value="3">three</option>
...
you will want to convince select2 to restore the originally selected value on reset, similar to how a native form works. To achieve this, first reset the native form and then update select2:
$('button[type="reset"]').click(function(event) {
// Make sure we reset the native form first
event.preventDefault();
$(this).closest('form').get(0).reset();
// And then update select2 to match
$('#d').select2('val', $('#d').find(':selected').val());
}
Just to that :)
$('#form-edit').trigger("reset");
$('#form-edit').find('select').each(function(){
$(this).change();
});
What I found works well is as follows:
if you have a placeholder option like 'All' or '-Select-' and its the first option and that's that you want to set the value to when you 'reset' you can use
$('#id').select2('val',0);
0 is essentially the option that you want to set it to on reset. If you want to set it to the last option then get the length of options and set it that length - 1. Basically use the index of whatever option you want to set the select2 value to on reset.
If you don't have a placeholder and just want no text to appear in the field use:
$('#id').select2('val','');
To achieve a generic solution, why not do this:
$(':reset').live('click', function(){
var $r = $(this);
setTimeout(function(){
$r.closest('form').find('.select2-offscreen').trigger('change');
}, 10);
});
This way:
You'll not have to make a new logic for each select2 on your application.
And, you don't have to know the default value (which, by the way, does not have to be "" or even the first option)
Finally, setting the value to :selected would not always achieve a true reset, since the current selected might well have been set programmatically on the client, whereas the default action of the form select is to return input element values to the server-sent ones.
EDIT:
Alternatively, considering the deprecated status of live, we could replace the first line with this:
$('form:has(:reset)').on('click', ':reset', function(){
or better still:
$('form:has(:reset)').on('reset', function(){
PS: I personally feel that resetting on reset, as well as triggering blur and focus events attached to the original select, are some of the most conspicuous "missing" features in select2!
Select2 uses a specific CSS class, so an easy way to reset it is:
$('.select2-container').select2('val', '');
And you have the advantage of if you have multiple Select2 at the same form, all them will be reseted with this single command.
Sometimes I want to reset Select2 but I can't without change() method. So my solution is :
function resetSelect2Wrapper(el, value){
$(el).val(value);
$(el).select2({
minimumResultsForSearch: -1,
language: "fr"
});
}
Using :
resetSelect2Wrapper("#mySelectId", "myValue");
For me it works only with any of these solutions
$(this).select2('val', null);
or
$(this).select2('val', '');
// Store default values
$('#filter_form [data-plugin="select2"]').each(function(i, el){
$(el).data("seldefault", $(el).find(":selected").val());
});
// Reset button action
$('#formresetbtn').on('click', function() {
$('#filter_form [data-plugin="select2"]').each(function(i, el){
$(el).val($(el).data("seldefault")).trigger('change');
});
});
If you want to reset forms in edit pages, you can add this button to forms
<button type="reset" class="btn btn-default" onclick="resetForm()">Reset</button>
and write your JS code like this:
function resetForm() {
setTimeout(function() {
$('.js-select2').each(function () {
$(this).change();
/* or use two lines below instead */
// var oldVal = $(this).val();
// $(this).select2({'val': oldVal});
});
}, 100);
}
Lots of great answers, but with the newest version none worked for me. If you want a generic solution for all select2 this is working perfectly.
Version 4.0.13 tested
$(document).ready(function() {
$('form').on('reset', function(){
console.log('triggered reset');
const $r = $(this);
setTimeout(function(){
$r.closest('form').find('.select2-hidden-accessible').trigger('change');
}, 10);
});
});
$(function(){
$("#btnReset").click(function(){
$("#d").select2({
val: "",
});
});
});
to remove all option value
$("#id").empty();