es5 简单继承

var father=function(){};
father.prototype={
    constructor:father,
    test:function(){
        console.log(1);
    }
}
var son=function(){};
son.prototype={
    constructor:son,
    dd:function(){
        console.log(23);
    }
};
var tem=function(son){
    Object.getOwnPropertyNames(son.prototype).forEach(i=>{
        this[i]=son.prototype[i];
    });
}
tem.prototype=new father();
tem.prototype.constructor=tem;
son.prototype=new tem(son);
son.prototype.constructor=son;
var r=new son();
console.log(r instanceof father);
console.log(r instanceof son);

使用了一个tem的function 然后将子类的prototype合并到实列本身 然后 r=new tem() r就是实例对象 然后 r实例具有 son的prototype属性就在r上面了