JS/Jquery: how to check whether dropdown has selected values? - javascript

I've googled and tried a number of ways to do this but none work for me so far. What I am looking for is quite simple: I want to be able to tell whether a dropdown has a selected value or not. The problem is that selectedIndex, :selected, val(), etc. do return results for the following case:
<select>
<option value="123">123</option>
<option value="234">234</option>
</select>
Obviously the browser will display this dropdown with the 123 option being selected but it will be selected only because there are no other options, in reality this dropdown doesn't have a selected value because there is no "selected" property. So basically I am trying to find how to tell apart the above dropdown from this one
<select>
<option selected value="123">123</option>
<option value="234">234</option>
</select>

var hasValue = ($('select > [selected]').length > 0);
Alternatively,
var hasValue = $('select').has('[selected]');

Quick solution:
<select>
<option selected></option>
<option value="123">123</option>
<option value="234">234</option>
</select>
Then see if you have a .val()

The approved answer doesn't seem to work for me.
Here is how I do it to check if all select options are selected:
if($('select option:selected').length > 0) {
/* Do your stuff here */
}

As far as I can tell, there is no functional distinction between your two examples. Essentially, the browser automatically selects the first option.
See, for example, the result of
$('option:selected')
on your first example.
If you really want to prevent this happening, you have two options. The first is to introduce a new, empty element into the select, per Jason's answer. The other option is to deselect the automatically selected value:
$(document).load(function(){
$('option:selected').attr('selected', false);
});
This clears the selection. Any result of $('select').val() that isn't an empty string will therefore be a change by the user.

Related

Set the first option select2

I want to set the first position to select2 dropdown by default, I have tried this but It doens´t work:
$('#mylist').val($('#mylist option:first-child').val()).trigger('change');
Other way that I tried;
$('#mylist').val(1);
But the problem is I don´t know what value is, because it is depend from a query and It will not always be the same value.
I did not set the dropdown values ​​from the HTML, but it is an input hidden and the values ​​are loaded in a query
I hope that anyone can help me
Regards!
If you using Select2 4.x just trigger change.select2
$('#mylist').val(1).trigger('change.select2');
please try with this:
$('#yourSelect2').val($('#yourSelect2 option:eq(1)').val()).trigger('change');
the value from eq() depends of the position that you want to select
This works for me:
$('#mylist option:eq(0)').prop('selected',true);
Please do this
$('select#mylist').val(1).select2();
It's better to use attribute specifiers and set that element's selected prop to true like so:
$('option[value="op2"]').prop('selected', true);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id="list">
<option value="op1">Option 1</option>
<option value="op2">Option 2</option>
<option value="op3">Option 3</option>
<option value="op4">Option 4</option>
</select>
Then change op2 to whatever the value attribute of the desired default option is.
this work for me :
$("#mylist").val($("#mylist option:first").val()).trigger('change');
juste remove -child
As you may know Select2 need data in particular format only [id="id_value",text="data_linked_to_id"]
Lets consider you want to select first item ,you should have its Id which is used by select2 to list all items.(let here first id be 1)
$('#selectElementId').val("1");
$('#selectElementId').trigger('change');
If want to set multiple items selected then pass array of ids.
ids=["1","3","4"]
$("#selectElementId").val(ids);
$("#selectElementId").trigger('change');
**OR**
$("#selectElementId").val(["1","3","4"]);
$("#selectElementId").trigger('change');
Step 1:
Select first option of your select(s) - works not only for select2
$('#myForm').find('select').find('option:eq(0)').attr('selected','selected');
Step 2:
Trigger select2 change
$('#myForm select').trigger('change.select2');

Want to add none as value in select multiple

I am using chosen.jquery.js for select field
<select chosen multiple data-placeholder="Select Body Part(s)"
ng-options="option.Name as option.Name for option in BodyPartList" ng-model="Body_Part">
<option value="" disabled>Select Body Part(s)</option>
</select>
But It shows only data-placeholder value in case of no data in model.
I want to show "Select Body Part(s)" as a option in list.
And user must not select this. Reason is that, I want to add dynamic "Unknown" value in list of Body_Parts. But it not reflect in list.
Same work for select having single selection.
I'm not seeing any problems with your code, as such. Like, I'm trying it and getting the visual behaviour I think you're wanting? Am I missing something?
Html just yours with ng-app etc, javascript is:
var myApp = angular.module('myApp', ['localytics.directives']);
myApp.controller('MyController', function($scope) {
$scope.BodyPartList = [
{ Name: "Arm" },
{ Name: "Leg" }
];
$scope.Body_Part = [];
});
Not sure if data-placeholder is actually doing anything.
Fiddle: http://jsfiddle.net/7187f6d9/
That said, it's not "working". In the fiddle I put a regular select box alongside the chosen one, and the chosen one doesn't seem to be writing to the ng-model correctly. I'm not sure what's up with that.
You can choose the below option
https://harvesthq.github.io/chosen/#optgroup-support
or push another item to the top of the array from server side as your custom label and disable it on client side with the help of ng-if and $index properties of ng-repeat and angularjs. If this make sense then its fine else i can give you a demo.
I hope your query is, you want show a place holder as current selected value but user shouldn't be able to select it.
Instead of making it disabled, make ithidden. Then display an error if a user doesn't select any other options, using the value of placeholder option.
A sample snippet is added below. If value of select is Error, write a case to throw a error back to user.
<select>
<option value="Error" hidden>Select any Company</option>
<option value="Toyota">Toyota</option>
<option value="Nissan">Nissan</option>
<option value="BMW">BMW</option>
</select>
Hope this helps! If not, ping me with your query. :)

Angular blank option selected

I'm banging my head against the wall on this one.
I have an array of objects that will be used to populate a select drop down:
CardCount = [{"ClientId": "0010", "Description": "0010 (206 Members)"}, {"ClientId": "0051", "Description": "0051 (1 Member)"}, ........]
When I attempt to use ng-options, the value of the option is set to the index, not to the ClientId as desired. To get the value in each option to be the ClientId, I have to use a ng-repeat in the options. Here is my html:
<select ng-model="CurrentClient">
<option ng-repeat="item in CardCount" value="{{item.ClientId}}">{{item.Description}}</option>
</select>
Initially, all is well, the select and options are generated correctly, and the first option is correct. Now, when a certain button is clicked somewhere else on the page, it becomes necessary to recreate this select and options with a smaller array of similar objects. However, doing so creates a blank option with a value of "? string:0010 ?". This is the option that is selected. Again, I cannot use ng-options to correct this problem because doing so doesn't set the value attribute in the option tags correctly. So, I added this to the option tag:
<option ng-repeat="item in CardCount" value="{{item.ClientId}}" ng-selected="CurrentClient == item.ClientId">{{item.Description}}</option>
Now, that does mark the correct option as selected. However, the drop down still shows the blank option. Here's the rendered html:
<select ng-model="CurrentClient">
<option value="? string:0010 ?"></option>
<option value="0010" selected="selected">0010 (206 Members)</option>
</select>
As you can see, it sets the correct option to selected. However, it sets it to selected="selected", and not just selected. When I inspect element and change selected="selected" to selected (remove the equals and everything after it), the drop down then correctly displays the correctly selected option.
Again, initially the select and options work great. The problem seems to happen only after the array that the select is created with is changed. How can I get this select and options working correctly after I change the array, and not show that first blank option?
Thanks!
Changed you option element to set value by default.
<option ng-repeat="item in CardCount track by item.ClientId"
value="{{item.ClientId}}">{{item.Description}}</option>
Hope this could help you. Thanks.
ng-options is definitely the way to go:
<select ng-model="selected.ClientId" ng-options="it.ClientId as it.Description for it in clientList">
<option value="">-</option>
</select>

Selecting first option of multiple select elements by Prototype JS

I want to select first option of all the select dropdowns having class required-entry in a page with Prototype JS. I have searched through SO questions and found many relevant questions but not what I exactly needed.
Thanks
It's been quite a while since I've done any Prototype.js. So this may not be the best way to go about it, but it should work.
let's say you have a page with:
<select class='required-entry'>
<option value='a'>AAA</option>
<option value='b'>BBB</option>
<option​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ value='c'>CCC</option>
</select>
<select class='required-entry'>
<option value='x'>XXX</option>
<option value='y'>YYY</option>
<option value='z'>ZZZ</option>
</select>​
You can grab the first option for each select by doing:
var firstOptions = [];
$$('.required-entry').each(function(sel, i) {
firstOptions.push($(sel).getElementsBySelector('option')[0]);
});
// firstOptions is now an array containing the first options
Now, I couldn't tell from your question if you wanted to retrieve the first options, or set the select value so that the first option is literally selected. Here's the later:
$$('.required-entry').each(function(sel, i) {
sel.selectedIndex = 0;
});

Use javascript to change second select list based on first select list option

I have two drop-down lists populated from an array of same dates stored in a database. I want to use javascript or jquery to change the second drop-down list based on the selection from the first list. So an example would be if the user selects 03/03/2012 in the first, start date list, then I'd like the second list to only show or allow future dates within the array. 3/3, 3/2 and 3/1 would either be greyed out or removed and 3/4, 3/5 would remain as selectable options. Can anyone help with the javascript coding or make another recommendation?
<select id='start_date' name='data[sDate]' title='Use the drop list'>
<option value="" selected="selected"> </option>
<option value="03/05/2012">03/05/2012</option>
<option value="03/04/2012">03/04/2012</option>
<option value="03/03/2012">03/03/2012</option>
<option value="03/02/2012">03/02/2012</option>
<option value="03/01/2012">03/01/2012</option>
</select>
<select id='end_date' name='data[eDate]' title='Use the drop list'>
<option value="" selected="selected"> </option>
<option value="03/05/2012">03/05/2012</option>
<option value="03/04/2012">03/04/2012</option>
<option value="03/03/2012">03/03/2012</option>
<option value="03/02/2012">03/02/2012</option>
<option value="03/01/2012">03/01/2012</option>
</select>
With your actual example, if the two lists are exactly the same then it's pretty simple if you work with index(). Look http://jsfiddle.net/elclanrs/7YrqY/
$('#start_date').change(function(){
var $selected = $(this).find('option:selected');
$('#end_date')
.find('option')
.prop('disabled', false)
.eq($selected.index()-1)
.nextAll()
.prop('disabled', true);
});
Here's a few different solutions, including server side. This is a common scenario and I'm sure you could find more examples on this site if you searched a bit more.
http://css-tricks.com/dynamic-dropdowns/
using jQuery
$(function(){ //when the page is loaded
$("#start_date").change(function(){ //register a anonymous function that will be called when the element with id=start_date changes his values
var start = $(this).val(); //gets the value of the element
$("#end_date option").each(function(i){//for each option of end_date
if(new Date($(this).val()).getTime() < new Date(start).getTime()){ //if the date of the element is before the start
$(this).hide(); //hide the element
}else{
$(this).show(); //shows the element
}
});
});
});
Ive not tested but is something like that

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