Develop Reference

How to get and change the text in a button?

I have a button with the class of
button.btn.btn-default.check-all
how do I find this button, get the text it says and change it with a find?
I tried something like this but not sure if it works
var r = $("button").find("check-all");

It appears that you have a button with multiple classes and you want to select the element based on all the classes. Simply use the following selector
$('button.btn.btn-default.check-all')
You can get the text by
$('button.btn.btn-default.check-all').text()
And can update by
$('button.btn.btn-default.check-all').text('your_updated_text');

You should do something like:
var element = $('button.btn.btn-default.check-all');
//save text in prevText
var prevText = element.text();
//now, change it!
element.text('text-changed');

Using class names to get an element might not be a good solution. My solution would be to use id attribute and use this id attribute to get the correct element.
See this fiddle
HTML
<button id="my-button" name="buttonName" onclick="change()">Hi</button>
and JS
alert(document.getElementById('my-button').innerHTML);
function change(){
document.getElementById('my-button').innerHTML='hello';
}
What I have done here is, used document.getElementById('my-button').innerHTML which gets the text of the button using document.getElementById(). The same thing can be used to set the text in a button.

This question lead to basic skills in jQuery. I truly recommande that you could find out jQuery Api documentation and read deeply into it. You can get a very good view of jQuery thus you can do much better and efficient in your work.
Here is the link that may help you with this question.
https://api.jquery.com/category/selectors/
https://api.jquery.com/category/attributes/

You can use the jQuery :contains() psuedo selector to create a variable that will pinpoint the button with the specified text. It can be any text, but be cautious if you have buttons with similar text because the return is not an exact match (to avoid this only input/search text that you know is unique to the button).
var r = $("button:contains('check-all')");
To change the text with the newly created variable you can use the jQuery .text() method.
r.text('check-none');
Fiddle Example
:contains() jQuery

Why the change function is not called in jquery mobile?

Hi I have the code to called the function on change the value of input field.where i just implement the jquery mobile datepicker but internally its change to
<input type="text" data-role="date" style="width:100%" class="to hasDatepicker" id="To" name="To">
(means adding hasdatepicker to that input field)So that It is not working .But when i change to click function it is working fine what might be the problem can any body tell and how to achieve that?
$('input.to').on('change',function() {

"To" is the id not a class, selector should be:
$('#To').on('change',function() {

You are accessing element by class name but To is not a class.
$('input[id=To]').on('change',function() {

As the above said, "To" is an id name, If you are insisting on using the (Element.Attribute) style I'd recommend to use $('input#To').on('clicked',function()).
You could also use $('input#To').clicked(function()) or just $("#To") which is preferred, since Id is an element Unique. You usually is the (Element.Attribute) style when you have a couple of elements, say <input></input> and you want to select a particular input by it's class, and not all the <input></input> elements.

You have to see how you are including the jQuery import. If you are including correctly, maybe have somewhere a function that killing your change. Verify whether have another call to this same event or a call to $('input.to').off('click') somewhere. But you can also call this method using $('#To').

Unexpected error using an indexed element id

I'm new to javascript and jquery, and stumbled upon an issue while writing a script.
My script is generated by php code which reads lines from a file, parses it and prints them out using arrays. js then validates form input, and outputs useful messages to the user.
I have successfully used js and jquery on $('#id').blur on various elements. However when I tried doing it on my indexed element, I came across this problem.
Code:
$('#NS_IN[0]').blur(function() {
alert("Called");
CopyNStoMain();
});
I noticed that this function would never get executed. I tried looking at the variables in console.
typeof($('#NS_IN[0]')) is an object; but typeof($('#NS_IN[0]').val()) is Undefined.
In my html code, I have:
<input type="text" id="NS_IN[0]" value="" name="NS[0]">
What am I doing wrong? If the id NS_IN[0] is defined and $(NS_IN[0]) refers to an object, shouldnt $(NS_IN[0]).val() exist and hold the value of the input box?

You need to escape the jquery selector characters.
$('#NS_IN\\[0\\]').blur(function() {
alert("Called");
CopyNStoMain();
});

You already have the answer here...I don't know how to tag your question as a duplicate.
//get
bla = $('#txt_name').val();
//set
$('#txt_name').val('bla');

In jQuery, the [] works in a different way, like:
div[id^="player_"]
So, one of the solutions, is to select the items which ID starts with something:
$("input[id^=NS_IN]").val();

It works when you use a different selector, as jquery uses the [] as an attribute selector itself. So use e.g. (see fiddle: http://jsfiddle.net/rePQm/1/ ):
$('input').click(function() { alert("clicked " + this.id); });
an element selector that selects all input elements and adds the click handler to all of them. See the selectors section of the jquery documentation at http://api.jquery.com/category/selectors/ for more possible selectors .

How to access elements from a certain form and certain type with jquery

so I have a page with multiple forms and I would like to be able to access input elements of type="datetime" within a particular form. I know I can do $('input[type="datetime"]') but that would give me all input tags on the page. I also cannot use the "form" attribute because not all browser use it (Sigh IE). Worse scenario for me is to do something like:
$(document.forms["..."].elements).each(function() {
if (this.type="datetime") {.....}
});
but I am sure this can be done in jQuery with one selector. Can someone tell me how do this with one selector?

Add id to your form and then select DOM inside of that form as below.
$('#form input[type="datetime"]')

Without seeing some HTML this is just a shot in the dark. But if you give your forms an id you can do:
$("#yourFormId input[type='datetime']");
If you do not have ids, but you know the number, then this might do it:
$("form:eq(4) input[type='datetime']");

There are multiple ways to do it
Solution 1.
use descendant selector
ex:
$('#yourform input[type="datetime"]') //or
$('.yourform input[type="datetime"]') //or
$('form:eq(3) input[type="datetime"]')
Solution 2:
Use context based look up
Ex:
$('input[type="datetime"]', yourform)

Disable all Radcomboboxes inside a div

I have several telerik radcomboboxes inside a div with various id's. I want to find all of them and disable them without using those id's like say finding the tag name using javascript.
Please help

Each RadControl renders a specific CSS class identifying the type of the control on the control container element. Additionally the JS object is an expando of the container element - control.
So, you can use this: $('.common-container-class-name .RadComboBox').each(function() { this.control.disable(); });

Not sure what a Rad Combo Box is but it seems like different types of input / text elements so try:
$('.someContainerDiv input').attr('disabled','disabled');
Change input for whatever the element is, like the <textarea> tag.