It is better to use .hasClass() when you want to check if an element has a particular class. This is because when an element has multiple class it is not trivial to check.

Example:

<div id='test' class='main divhover'></div>

Where:

$('#test').attr('class');        // returns `main divhover`.

With .hasClass() we can test if the div has the class divhover.

$('#test').hasClass('divhover'); // returns true
$('#test').hasClass('main');     // returns true

Be Careful , Perhaps , you have a class and a subclass .

  <div id='id' class='myclass mysubclass' >dfdfdfsdfds</div>

If you use previous solutions , you will have :

myclass mysubclass

So if you want to have the class selector, do the following :

var className = '.'+$('#id').attr('class').split(' ').join('.')

and you will have

.myclass.mysubclass

Now if you want to select all elements that have the same class such as div above :

   var brothers=$('.'+$('#id').attr('class').split(' ').join('.'))

that means

var brothers=$('.myclass.mysubclass')

Update 2018

OR can be implemented with vanilla javascript in 2 lines:

  const { classList } = document.querySelector('#id');
  document.querySelectorAll(`.${Array.from(classList).join('.')}`);

This is to get the second class into multiple classes using into a element

var class_name = $('#videobuttonChange').attr('class').split(' ')[1];

you can simply use,

var className = $('#id').attr('class');

If your <div> has an id:

​<div id="test" class="my-custom-class"></div>​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

...you can try:

var yourClass = $("#test").prop("class");

If your <div> has only a class, you can try:

var yourClass = $(".my-custom-class").prop("class");

If you're going to use the split function to extract the class names, then you're going to have to compensate for potential formatting variations that could produce unexpected results. For example:

" myclass1  myclass2 ".split(' ').join(".")

produces

".myclass1..myclass2."

I think you're better off using a regular expression to match on set of allowable characters for class names. For example:

" myclass1  myclass2  ".match(/[\d\w-_]+/g);

produces

["myclass1", "myclass2"]

The regular expression is probably not complete, but hopefully you understand my point. This approach mitigates the possibility of poor formatting.

To complete Whitestock answer (which is the best I found) I did :

className = $(this).attr('class').match(/[\d\w-_]+/g);
className = '.' + className.join(' .');

So for " myclass1 myclass2 " the result will be '.myclass1 .myclass2'

<div id="elem" class="className"></div>

With Javascript

document.getElementById('elem').className;

With jQuery

$('#elem').attr('class');

OR

$('#elem').get(0).className;

You can get class Name by two ways :

var className = $('.myclass').attr('class');

OR

var className = $('.myclass').prop('class');

If we have a code:

<div id="myDiv" class="myClass myClass2"></div> 

to take class name by using jQuery we could define and use a simple plugin method:

$.fn.class = function(){
  return Array.prototype.slice.call( $(this)[0].classList );
}

or

 $.fn.class = function(){
   return $(this).prop('class');
 } 

The use of the method will be:

$('#myDiv').class();

We have to notice that it will return a list of classes unlike of native method element.className which returns only first class of the attached classes. Because often the element has more than one class attached to it, I recommend you not to use this native method but element.classlist or the method described above.

The first variant of it will return a list of classes as an array, the second as a string - class names separated by spaces:

// [myClass, myClass2]
// "myClass myClass2"

Another important notice is that both methods as well as jQuery method

$('div').prop('class');

return only class list of the first element caught by the jQuery object if we use a more common selector which points many other elements. In such a case we have to mark the element, we want to get his classes, by using some index, e.g.

$('div:eq(2)').prop('class');

It depends also what you need to do with these classes. If you want just to check for a class into the class list of the element with this id you should just use method "hasClass":

if($('#myDiv').hasClass('myClass')){
   // do something
}

as mentioned in the comments above. But if you could need to take all classes as a selector, then use this code:

$.fn.classes = function(){
   var o = $(this);
   return o.prop('class')? [''].concat( o.prop('class').split(' ') ).join('.') : '';
 } 

 var mySelector = $('#myDiv').classes();

The result will be:

// .myClass.myClass2

and you could get it to create dynamically a specific rewriting css rule for example.

Regards

If you do not know the class name BUT you know the ID you can try this:

<div id="currentST" class="myclass"></div>

Then Call it using :

alert($('#currentST').attr('class'));

If you want to get classes of div and then want to check if any class exists then simple use.

if ( $('#div-id' ).hasClass( 'classname' ) ) {
    // do something...
}

e.g;

if ( $('body').hasClass( 'home' ) ) {
    $('#menu-item-4').addClass('active');
}

Try it

HTML

<div class="class_area-1">
    area 1
</div>

<div class="class_area-2">
    area 2
</div>

<div class="class_area-3">
    area 3
</div>

jQuery

<script src="https://code.jquery.com/jquery-1.11.3.js"></script>
<script type="application/javascript">
    $('div').click(function(){
        alert($(this).attr('class'));
    });
</script>

This works too.

const $el = $(".myclass");
const className = $el[0].className;

if we have single or we want first div element we can use

$('div')[0].className otherwise we need an id of that element

Best way to get class name in javascript or jquery

attr() attribute function is used to get and set attribute.

Get Class

jQuery('your selector').attr('class');  // Return class

Check class exist or not

The hasClass() method checks if any of the selected elements have a specified class name.

 if(jQuery('selector').hasClass('abc-class')){
        // Yes Exist
    }else{
        // NOt exists
    }

Set Class

jQuery('your selector').attr('class','myclass');  // It will add class to your selector

Get Class on Click of button using jQuery

jQuery(document).on('click','button',function(){
     var myclass = jQuery('#selector').attr('class');
});

Add class if selector have no any class using jQuery

if ( $('#div-id' ).hasClass( 'classname' ) ) {
        // Add your code
    }

Get the second class into multiple classes using into a element

Change array position in place of [1] to get particular class.

var mysecondclass = $('#mydiv').attr('class').split(' ')[1];

Direct way

myid.className

console.log( myid.className )

<div id="myid" class="myclass"></div>