Develop Reference

How do I set a certain number of options in select 2?

I need to make an analog of the size attribute in the Select2 plugin as in the default select. I can't find it in the docks.
Here's how implemented in default
Sorry for English :)

In html you can use disabled ether on the entire selection or option as showing in your image, here is an example :
<select>
<option value="1" disabled>option 1</option>
<option value="2">option 2</option>
<option value="3">option 3</option>
<option value="4" disabled>option 4</option>
</select>
as you can see you can't select option 1 and 4

Angular Dropdown menu does not show default value

With regular html select menus, if you create an option element with selected and disabled attributes and give that option text, then that text will display in the select menu by default. Here is basic html:
<select name="myname">
<option selected disabled>Select one...</option>
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
</select>
This is what pages looks like:
But in the below isolated code, I demonstrate that Angular is intrusively not showing the option text:
https://github.com/lovefamilychildrenhappiness/DropDownNoShowDefaultValue
// app.component.html
<h1>Select Box does not show default value: </h1>
<app-select-box
[options]="collection"
></app-select-box>
// select-box.component.html
<select
[value]="value"
[disabled]="disabled">
<option selected disabled value="">Select one...</option>
<option *ngFor="let option of options">{{option}}</option>
</select>
What is causing Angular to disrupt the native html behavior of select boxes?

This is because your select value is bound to a variable called value which is undefined initially. As per the html, there is no option with a value of undefined, so nothing gets selected. Your Select one... option has an empty string value. So to fix this, initialize value in your component to an empty string.
value: string = '';

just put the option to be selected in the first place.
<option value="0">value to be selected<option>
<option value="1">next<option>
<option value="2">Continues<option>

Select an option from a drop down using the class?

I am looking for a way to select an option from a drop down list using the item class, and containing text. For example
<select class="mySelect">
<option value="Test 1">Test 1</option>
<option value="Test 2">Test 2</option>
<option value="Test 3">Test 3</option>
</select>
I cannot use the select ID because it might change, but the class will always be the same. I want to do, if option has the word Test, make the color of the word "Test" blue.
I think I can handle the color assignment, but what I am having an issue with is using the class to select the child options. I have tried:
$('.mySelect option:contains("Test")');
However I get an error that this is not a valid selector.
I also tried:
$('.mySelect select option:contains("Test")');
Finally, thanks to comments, I tried
$('select option[value*="Test"]')
However, this only returns the first item.
OK, here is the actual code in production, lets see if this changes anything.
<select onclick="SetChoiceOption('ctl00_ctl40_g_6a07f243_6d33_4cb8_bf98_47743415ee4a_ctl00_ctl05_ctl05_ctl00_ctl00_ctl05_ctl00_DropDownButton')" name="ctl00$ctl40$g_6a07f243_6d33_4cb8_bf98_47743415ee4a$ctl00$ctl05$ctl05$ctl00$ctl00$ctl05$ctl00$DropDownChoice" id="ctl00_ctl40_g_6a07f243_6d33_4cb8_bf98_47743415ee4a_ctl00_ctl05_ctl05_ctl00_ctl00_ctl05_ctl00_DropDownChoice" title="Category: Choice Drop Down" class="ms-RadioText">
<option selected="selected" value=""></option>
<option value="Meeting Test">Meeting Test</option>
<option value="Work hours Test">Work hours Test</option>
<option value="Business Test">Business Test</option>
<option value="Holiday Test">Holiday Test</option>
<option value="Get-together Test">Get-together Test</option>
<option value="Gifts Test">Gifts Test</option>
<option value="Birthday Test">Birthday Test</option>
<option value="Anniversary Test">Anniversary Test</option>
</select>
Here is a fiddle that returns each as text, but, somehow does not return the elements.
https://jsfiddle.net/3hgpw778/

$('.mySelect option:contains("Test")'); is valid and is selecting the three options. but as an alternative you can try this:
$('select option[value^="Test"]')

$$('select option[value*="Test"]');
was the answer. I got the additional piece from Simple jQuery selector only selects first element in Chrome..?

Select a value in a specific optgroup

I have a select with multiple optgroups
For example
<select id="Numbers">
<option value="0">Select One</option>
<optgroup label="A" id="A">
<option value="123">123</option>
<option value="456">456</option>
</optgroup>
<optgroup label="B" id="B">
<option value="123">123</option>
<option value="456">456</option>
</optgroup>
</select>
Since the values in both optgroups are the same, is there a way to select an option depending on its optgroup?
So I want to select the option with the value of "123" in optgroup with the id of "B"

As you have provided id B. You can use ID selector and Attribute Value Selector
You can use
$('#B option[value="123"]').prop('selected', true)
DEMO

Using jquery you can limit the selection to the children of the optgroup you want. In this case:
$("optgroup#B > option[value='123']").attr("selected", "selected");
Should do the trick.

SORRY, THOUGHT THEY WERE CHECKBOXES. THIS WILL NOT WORK.
Do you mean automatically show it as checked, on loading the page? If so use jQuery:
$("#B").children('.myCheckbox').prop('checked', true);

on option item is selected

EDIT:
I forgot http:// on the links. This is not my problem. I'll fix the question...
i have some options, like this:
<select class="mySelect">
<option value="http://www.url1.com">Url 1</option> <!--Default displayed--->
<option value="http://www.url2.com">Url 2</option>
<option value="http://www.url3.com">Url 3</option>
</select>
To this i have a jquery listener, looks like this:
$('.mySelect').change(function(){
window.location.replace($(this).val());
});
Since this just responds to a change made, i can't be redirected to "www.url1.com". What should i use? I only get suggestions for change on google.
EDIT 2: I've got a bunch of solutions on using a dummy as first option. I also got the other solution of using a button to read the selected option and then redirect, but that's not usable in the project i'm working on, even if these are really good solutions otherwise.
In this case, i want it to listen for usage, even if the change is made to itself, like i'm selecting the first option (that's selected by default) i want it to do something with it - In the case above a redirect. I'll leave it open if someone have a good solution to this problem.

Try putting in an empty valued first option:
<select class="mySelect">
<option value="">Please select...</option>
<option value="http://www.url1.com">Url 1</option>
<option value="http://www.url2.com">Url 2</option>
<option value="http://www.url3.com">Url 3</option>
</select>
You can then amend your jQuery to make sure there is a value before redirecting:
$('.mySelect').change(function(){
var value = $(this).val();
if (value != "") {
window.location.replace(value);
}
});
Example fiddle
Note also that http:// (or whichever protocol you're using) is required on the link values.
Updated
If you would prefer to not have the dummy option, you would need to change the logic to work on button click:
<select class="mySelect">
<option value="http://www.url1.com">Url 1</option>
<option value="http://www.url2.com">Url 2</option>
<option value="http://www.url3.com">Url 3</option>
</select>
<button id="redirect">Go</button>
$("#redirect").click(function() {
window.location.replace($(".mySelect").val());
});

You have to put http:// also
window.location.replace("http://"+$(this).val());

One option can be that you change the first option like
<select class="mySelect">
<option value="select">Select URL</option> <!--Default displayed--->
<option value="www.url1.com">Url 1</option>
<option value="www.url2.com">Url 2</option>
<option value="www.url3.com">Url 3</option>
</select>
or you can use click jquery event for combo box .

<form>
<select class="mySelect">
<option value="" selected="selected">Please Select</option>
<option value="www.url1.com">Url 1</option>
<option value="www.url2.com">Url 2</option>
<option value="www.url3.com">Url 3</option>
</select>
</form>​
$(".mySelect").change( function() {
var n = $(this).val();
if(n != "") {
window.location.assign("http://"+n);
}
});​