How to select first class in a list of class definition for an element

I have these elements :

<div id="contentoDinamico">    
    <div id="item_box_3777" class="index0 itemContenutoDinamico attivo">
    <div id="item_box_3792" class="index4 itemContenutoDinamico">
</div>

and this function :

开发者_StackOverflow$("#contentoDinamico div").attr('class', function(i, e) {
    a.push(e);
});

but I'd like to push only first class for each div child; so, in the example, index0 and index4, not index0 itemContenutoDinamico attivo and index4 itemContenutoDinamico.

How can I do this?

HTML5 compatible browsers add a classList property to elements which you can index directly. Alternatively you'd have to split the class value by space characters:

$("#contentoDinamico div").each(function(i, e) {
     if ('classList' in this) {
         a.push(this.classList[0]);
     } else {
         var cn = this.className;
         var ca = cn.split(' ');
         a.push(c[0]);
     }
}

The space splitting version might break if you have leading spaces in your class attribute.

Split the class that you return by a space, and then there you have it:

.split(/\s/)