javascript 的类式继承（构造函数）

<script type="text/javascript">
//类式继承（构造函数）
var father = function(){
    this.age = 52;
    this.say =function(){
        alert('hello i am'+this.name+'and i am'+this.age+'years old')
    }
}
var child = function(){
    this.name = 'bill';
    father.call(this);
}
var man = new child();
man.say();

</script>