<html><body><h2>JavaScript 对象属性</h2><p>您可以向现有对象添加新属性。</p><p id="demo"></p><script>var person = { firstname:"John", lastname:"Doe", age:50, eyecolor:"blue"};person.nationality = "English";document.getElementById("demo").innerHTML =person.firstname + " is " + person.nationality + ".";</script></body></html>