Add and remove a property named "color":
$(document).ready(function(){
$("button").click(function(){
var $x = $("div");
$x.prop("color", "FF0000");
$x.append("The color property has the following value: " + $x.prop("color"));
$x.removeProp("color");
$x.append("<br>Now the color property has the following value: " + $x.prop("color"));
});
});