Is there an "exists" function for jQuery?

I had a case where I wanted to see if an object exists inside of another so I added something to the first answer to check for a selector inside the selector..

// Checks if an object exists.
// Usage:
//
//     $(selector).exists()
//
// Or:
// 
//     $(selector).exists(anotherSelector);
jQuery.fn.exists = function(selector) {
    return selector ? this.find(selector).length : this.length;
};