Question

If there is an element with the class myclass in the #main element, I want to alert ok but in my example it always shows no, how can fix this?

Demo: http://jsfiddle.net/mF2K6/1/

<form>
    <div id="main">
        <div class="myclass"></div>
    </div>
    <button>Click Me</button>
</form>


$('button').live('click', function (e) {
    e.preventDefault();
    //var copy_html = $('#main').clone();
    //if ($('#main').hasClass('myclass')) {
    if ($('#main').is('.myclass')) {
        alert('ok');
    } else {
        alert('no');
    }
})

Answer 1

To check sub-elements for myclass, use this:

if ($('#main').find('.myclass').length != 0)

or this:

if ($('#main .myclass').length != 0)