javascript中的构造函数和this关键字

<script language="javascript">
function person(name,age)
{ this.name = name;
  this.age = age;
  this.say = sayFunc;
}
function sayFunc()
{ alert(this.name+":"+this.age);
}
var person1 = new person("xiaxia",27);
person1.say();
var person2 = new person("bobo",26);
person2.say();
</script>