jQuery "hasParent"

For a clean re-usable solution, consider extending the jQuery.fn object with a custom method used for determining the presence of a particular ancestor for any given element:

// Extend jQuery.fn with our new methodjQuery.extend( jQuery.fn, {    // Name of our method & one argument (the parent selector)    within: function( pSelector ) {        // Returns a subset of items using jQuery.filter        return this.filter(function(){            // Return truthy/falsey based on presence in parent            return $(this).closest( pSelector ).length;        });    }});

This results in a new method, $.fn.within, that we can use to filter our results:

$("li").within(".x").css("background", "red");

This selects all list items on the document, and then filters to only those that have .x as an ancestor. Because this uses jQuery internally, you could pass in a more complicated selector:

$("li").within(".x, .y").css("background", "red");

This will filter the collection to items that descend from either .x or .y, or both.

Fiddle: http://jsfiddle.net/jonathansampson/6GMN5/

if ( $('.foo').parents('.parentSelector').length ) { // has parent }

If I understand your question correctly, this would do:

$.fn.hasAncestor = function(a) {    return this.filter(function() {        return !!$(this).closest(a).length;    });};$('.element').hasAncestor('.container').myAction();<div class="container">  <span>    <strong class="element">strong</strong>  </span></div>