(2) prototype-based class inheritance

1 version 1

var Animal = function(){        this.init(this,arguments);    };    //init    Animal.prototype.init = function(color){        this.color = color;    };    Animal.prototype.breath = function(){        console.log("breath");    };    var Dog = function(){};    Dog.prototype = new Animal();    Dog.prototype.init("white");    Dog.prototype.getColor = function(){        console.log(this.color);    };    var dog = new Dog();    dog.breath();//breath    dog.getColor();//white

(1) The Dog class inherits the animal class. This inheritance belongs to the prototype inheritance, that is, the dog prototype has an animal class instance.

 

2 version 2 class library add inheritance

var Class = function(parent){        var klass = function(){            this.init.apply(this,arguments);        };        if(parent){            var subClass = function(){};            subClass.prototype = parent.prototype;            klass.prototype = new subClass();        }        //init        klass.prototype.init = function(){};        klass.fn = klass.prototype;        klass.fn.parent = klass;        //add class property        klass.extend = function(obj){            var extended = obj.extended;            for(var i in obj){                klass[i] = obj[i];            }            if(extended) extended(klass);        };        //add prototype property        klass.include = function(obj){            var included = obj.included;            for(var i in obj){                klass.fn[i] = obj[i];            }            if(included) included(klass);        };        return klass;    };    var Animal = new Class();    Animal.include({        breath:function(){            console.log(‘breath‘);        }    });    var Cat = new Class(Animal);    var tommy = new Cat();    tommy.breath();

You can read this code carefully.

 if(parent){            var subClass = function(){};            subClass.prototype = parent.prototype;            klass.prototype = new subClass();        }

Upload the animal function again, create a local subclass prototype to point to the animal prototype, and then point the Klass prototype to the subclass instance to prevent prototype pollution.

(2) prototype-based class inheritance