这个原型链的问题我弱弱的问下为啥没有
window.onload=function(){
function first(){
this.firstV=1;
};
first.prototype.getFirstVal=function(){
return this.firstV;
};
function second(){
this.secondV=2;
}
second.prototype=new first();
second.prototype.getSecondVal=function(){
return this.secondV;
}
function third(){
this.thirdV=3;
}
third.prototype=new second();
third.prototype.getThirdVal=function(){
return this.thirdV;
}
alert(second.prototype.getSecondVal());