Something

var testFor = function(obj) {
        for (var i in obj) {
          alert(typeof obj[i]);
        }
      };

      var testEach = function(obj) {
        $.each(obj, function(i) {
          alert(typeof this);
        });
      };

      data = {
        test: false
      };
      testFor(data);  // alerts "boolean"
      testEach(data); // alerts "object"