JavaScript common object class creation code and analysis of advantages and disadvantages_js object-oriented

There are several ways to build a class in Javascript:
1.Factory method

Copy code The code is as follows:

function createCar(){
var car = new Object();
car.color="b";
car.length=1;
car.run=function(){alert(”run”);}
return car;
}

After defining such a function, you can use:
var car1 = createCar();
var car2 = createCar();
to create a new object. The problem with this method is that every time a car object is created, the run Function must be re-created. It is a waste of memory.

2.Constructor method

Copy code The code is as follows:

function Car(){
this.color=”b”;
this.length=1;
this.run=function(){alert(”run”);}
}
var car1=new Car();
var car2=new Car();

This is the most basic method, but it also has the same problems as the factory method

3.prototype method

Copy code The code is as follows:

function Car(){
}
Car.prototype.color=”b”;
Car.prototype.length=1;
Car.prototype.run=function(){alert ("run");
}

The disadvantage of this method is that when this class has a reference attribute, changing this attribute of one object will also change the attributes of other objects
For example:

Copy code The code is as follows:

Car.prototype.data1=new Array() ;
var car1=new Car();
var car2=new Car();
car1.data1.push("a");

At this time, car2 .data also contains the "a" element

4. Prototype/Constructor hybrid method [Commonly used]

Copy code The code is as follows:

function Car(){
this.color=”b”;
this.length=1;
this .data1=new Array();
}
Car.prototype.run=function(){
alert("dddd");
}

This kind This method eliminates those shortcomings. It is currently a widely used method

5. Dynamic prototype method [commonly used]

Copy Code The code is as follows:

function Car(){
this.color="b";
this.length=1;
this.data1=new Array();

if(typeof Car.initilize==”undefined”){
Car.prototype.run=function(){alert(”a”);}
}

Car.initilize=true;
}

Among these methods, the most commonly used are hybrid prototype/constructor and dynamic prototype methods