Use hidden new to create objects_jquery-JS Tutorial-php.cn

Use hidden new to create objects_jquery

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Release： 2016-05-16 18:08:52

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Many times we write classes like this and then use new to create objects.

Copy code The code is as follows:

 
function Person(name,age){ 
this .name=name; 
this.age=age; 
} 
Person.prototype={ 
setName : function(n){this.name=n;}, 
getName : function (){return this.name;} 
} 
var p = new Person('jack',25); 

Change to this

Copy code The code is as follows:

 
function Person(name,age){ 
//The condition is changed to (this== window) or (this==self) or (this.constructor!=Object) 
if(!this.setName){ 
return new Person(name,age); 
} 
this. name=name; 
this.age=age; 
} 
Person.prototype={ 
setName : function(n){this.name=n;}, 
getName : function( ){return this.name;} 
} 
var p = Person('jack',25); 

Note that this class has the following additions compared to the top way of writing classes.

Copy code The code is as follows:

 
if(!this.setName){ 
return new Person(name,age); 
} 

Okay, the way to create an instance (object) of the class has also become as follows

Copy code The code is as follows:

var p = Person('jack',25);

This way of creation ( Function call) is less "new_", new and spaces than the above one. It is actually new inside the class. This method can reduce 4 bytes each time an object is created.
If the if judgment condition inside the class is replaced by a non-prototype attribute, such as this.name. The program will prompt an error: too much recursion

Copy code The code is as follows:

 
function Person(name ,age){ 
if(!this.name){ 
return new Person(name,age); 
} 
this.name=name; 
this.age=age; 
} 
Person.prototype={ 
setName : function(n){this.name=n;}, 
getName : function(){return this.name;} 
} 
var p = Person('jack',25); 