jquery.exists.js

console.log($('some.selector').exists());

$('some.other.selector').exists(function(){
  /* I've got the maaagic in meeee */
}) 

jQuery.fn.exists.coffee

do (window, jQuery) ->
  unless jQuery.fn.exists
    unless callback? or typeof callback isnt 'function'
      callback = => @length > 0
    callback.apply this
  return

jQuery.fn.exists.js

(function(window, jQuery) {
  var callback;
  if (!jQuery.fn.exists) {
    if (!((typeof callback !== "undefined" && callback !== null) || typeof callback !== 'function')) {
      callback = (function(_this) {
        return function() {
          return _this.length > 0;
        };
      })(this);
    }
    callback.apply(this);
  }
})(window, jQuery);