Explanation of js Object Inheritance

// Inheritance in javascript-first Inheritance Method: Object impersonating
Function Parent (name)
{
This. name = name;
This. getInfo = function ()
{
Document. write ("Father's name is:" + name + "<br/> ");
}
}
Function Child (name, age)
{
// This is the most important three-line code to inherit the parent class
This. mehod = Parent; // The Code assigns the Parent object to this. method, which inherits the attributes and methods of the Parent class.
This. mehod (name); // this code initializes an attribute of the parent class.
Delete this. method; // delete because menthod has no effect

This. age = age;
This. getChildInfo = function ()
{
Document. write ("Son name:" + this. name + ", age:" + this. age );
}
}
 
Var parent = new Parent ("dad ");
// Parent. getInfo ();
Var child = new Child ("son", 24 );
// Child. getInfo ();
// Child. getChildInfo ();

 

// The call method is a method of every Function. Therefore, every Function we define has this method. The first parameter of the call method must be passed to this, the following parameters are passed to the function at a time.
Function Test (name, age)
{
This. name = name;
This. age = age;

This. getInfo = function ()
{
Document. write ("name:" + this. name + ", age:" + this. age );
}
}
Var obj1 = new Object ();
Obj1.sex = "male ";
Obj1.get = function ()
{
Document. write ("name:" + this. name + "age:" + this. age + "sex" + this. sex );
}
// Call text. call is equivalent to call test.
// Note: obj1 inherits the test function and its attributes and methods.
Test. call (obj1, "Cao Huan", 21 );
Alert (obj1.name );
Obj1.getInfo ();
Obj1.get ();

 

// Call method implementation inheritance
/* Function Parent (name)
{
This. name = name;
This. getParentInfo = function ()
{
Document. write ("name:" + this. name + "<br/> ");
}
}
 
Function Child (password)
{
Parent. call (this, "Cao Huan ");
This. password = password;
This. getChildInfo = function ()
{
Document. write ("name:" + this. name + ", password:" + this. password + "<br/> ");
}
}
 
Var p = new Parent ("");
// P. getParentInfo ();
Var c = new Child ("123456 ");
// C. getParentInfo ();
// C. getChildInfo ();

 

// The third method of Object Inheritance: apply and call
Function Parent (name)
{
This. name = name;
This. getInfo = function ()
{
Document. write ("name:" + this. name, "<br/> ");
}
}
 
Function Child (password)
{
Parent. apply (this, ["Cao Huan"]); // the difference between this and call is that the second parameter is passed as an array, while the call parameter is transmitted as parameters.
This. password = password;
This. getChildInfo = function ()
{
Document. write ("name:" + this. name + ", password:" + this. password, "<br/> ");
}
}
 
Var p = new Parent ("");
// P. getInfo ();
Var c = new Child ("password ");
// C. getInfo ();
// C. getChildInfo ();

 

// Implement inheritance in the prototype chain mode. The defect is that parameters cannot be passed to the constructor.
Function ParentPrototype (){}
ParentPrototype. prototype. name = "James ";
ParentPrototype. prototype. getInfo = function ()
{
Document. write ("name:" + this. name + "<br/> ");
}
Function ChildPrototype (){};
// The Key to integration is the code.
ChildPrototype. prototype = new ParentPrototype ();
ChildPrototype. prototype. password = "password ";
ChildPrototype. prototype. getAllInfo = function ()
{
Alert ("asd ");
Document. write ("name:" + this. name + ", password:" + this. password );
}
 
Var child = new ChildPrototype ();*/
// Child. getInfo ();
// Child. getAllInfo ();
// Prototype chain inheritance method that can pass parameters (composite): This method is recommended.
 
Function ParentFh (name)
{
This. name = name;
}
ParentFh. prototype. getInfo = function ()
{
Document. write ("name:" + this. name, "<br/> ");
}
 
Function ChildFh (name, password)
{
This. password = password;
ParentFh. call (this, name );
}
ChildFh. prototype = new ParentFh ();
ChildFh. prototype. getAllInfo = function ()
{
Document. write ("name:" + this. name + ", password:" + this. password );
}
Var parentFh = new ParentFh ("Cao Huan ");
ParentFh. getInfo ();
Var childFh = new ChildFh ("Cao Juan", "password ");
ChildFh. getAllInfo ();