JavaScriptが持つ属性Obj.hasOwnProperty(obj.属性)

<script>
function Person(obj){
	this.name = obj.name;
	this.age = obj.age;
}

var one = new Person({
	name : "hello",
	age : 22
});

alert("hasOwnProperty: " + one.hasOwnProperty("name"));

</script>