JavaScript constructor method definition object (reprint)

• JavaScript is a dynamic language that allows you to add properties to objects at run time, or to Delete (delete) Properties

Property Name: The method name is also possible. Because the function itself is an object.

 
 

  
  
 
   
JavaScript array sorting
 
  
 
 
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Several ways to define objects in JavaScript (there is no concept of classes in JavaScript, only objects)
 
    
 
     
The first way: Extend its properties and methods based on existing objects
 
    
 
   
 
  
<script type= "Text/javascript" >//01. Expands its properties and methods based on existing objects Var object=new object (); Object.username= "Zhangsan"; o Bject.sayname=function (name) {    this.username=name;    alert (this.username);} alert (object.username); Object.sayname ("Lisi"); alert (object.username);</script>
 
  

  
   
 
    
This approach has limitations because JavaScript does not have the concept of a class like Java, writes a class, and then new can get an object with these properties and methods.
 
    
At this point, if you want to have object2 can only write a copy of the above code, which is not very good.
 
   
 
  

 
  

  
   
 
    
The second way: Factory mode
 
   
 
  
 
  

  
   
 
    
Similar to the static factory method in Java.
 
   
 
  
Press CTRL + C to copy the code<textarea></textarea>Press CTRL + C to copy the code
There are drawbacks to creating objects in this way (each object has a get method that wastes memory) and an improved factory approach (all objects share a Get method):
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The Third Way: constructor method defining an object
 
    
 
   
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Fourth Way: prototype (Prototype) way to create an object
 
      
 
     
 
    
Prototype is a property in an object, and all person objects can also have prototype properties.

 
    

  
     
 
      
You can add some properties to the object's prototype, methods.
 
     
 
    
The disadvantage of creating an object with a simple prototype: ① cannot pass arguments, it can only change its value after the object is created

 
    

  
     
 
      
② may cause program errors
 
     
 
    
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Simply using a prototype to define an object cannot be used to assign an initial value to a property in a constructor, but only after the object has been generated, the property value is changed.

 
      

  
       
 
        
The fifth way: Use the prototype + constructor to define the object---- recommended
 
        
 
         
Properties between objects do not interfere with each other
 
         
Share the same method across objects
 
        
 
       
 
      
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The Sixth way: Dynamic prototyping mode---- Recommended Use
 
        
 
       
 
       

  
        
 
         
 in the constructor, the flags allow all objects to share a method, and each object has its own properties. 
 
        
 
       
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Tags: JavaScript, objects, constructs
JavaScript constructor method definition object (reprint)