js实现继承的五种方式

function Parent(firstname)
{
    this.fname=firstname;
    this.age=;
    this.sayAge=function()
    {
        console.log(this.age);
    }
}
function Child(firstname)
{
    this.parent=Parent;
    this.parent(firstname);
    delete this.parent;
    this.saySomeThing=function()
    {
        console.log(this.fname);
        this.sayAge();
    }
}
var mychild=new  Child("李");
mychild.saySomeThing();  

function Parent(firstname)
{
    this.fname=firstname;
    this.age=;
    this.sayAge=function()
    {
        console.log(this.age);
    }
}
function Child(firstname)
{  
 
    this.saySomeThing=function()
    {
        console.log(this.fname);
        this.sayAge();
    }
   this.getName=function()
   {
       return firstname;
   }  
 
}
var child=new Child("张");
Parent.call(child,child.getName());
child.saySomeThing();  

function Parent(firstname)
{
    this.fname=firstname;
    this.age=;
    this.sayAge=function()
    {
        console.log(this.age);
    }
}
function Child(firstname)
{  
 
    this.saySomeThing=function()
    {
        console.log(this.fname);
        this.sayAge();
    }
    this.getName=function()
    {
        return firstname;
    }  
 
}
var child=new Child("张");
Parent.apply(child,[child.getName()]);
child.saySomeThing();  

function Parent()
{  
 
    this.sayAge=function()
    {
        console.log(this.age);
    }
}
function Child(firstname)
{
    this.fname=firstname;
    this.age=;
    this.saySomeThing=function()
    {
        console.log(this.fname);
        this.sayAge();
    }
}  
 
Child.prototype=new  Parent();
var child=new Child("张");
child.saySomeThing();  

function Parent()
{  
 
    this.sayAge=function()
    {
        console.log(this.age);
    }
}  
 
Parent.prototype.sayParent=function()
{
   alert("this is parentmethod!!!");
}  
 
function Child(firstname)
{
    Parent.call(this);
    this.fname=firstname;
    this.age=;
    this.saySomeThing=function()
    {
        console.log(this.fname);
        this.sayAge();
    }
}  
 
Child.prototype=new  Parent();
var child=new Child("张");
child.saySomeThing();
child.sayParent();