JavaScript 原型(prototype)函数问题

Question

我构建了一个构造函数，并向其原型(prototype)添加了 3 个函数。 当我尝试从原型(prototype)调用函数时，出现此错误

类型错误:未定义不是函数(评估“fireOne.addLogs(8)”)

请有人告诉我我做错了什么。我无法弄清楚。

提前致谢

 function SignalFire(ID, startingLogs){
   this.fireID = ID;
   this.logsLeft = startingLogs;
 }


 var fireOne = new SignalFire(1, 20);
 var fireTwo = new SignalFire(2, 18);
 var fireThree = new SignalFire(3, 24);




 SignalFire.prototype = {

   addLogs: function(numLogs){
     this.logsLeft += numLogs;
   },


   lightFire: function(){
     alert("Whoooooosh!");
   },

   smokeSignal: function(message) {
     if (this.logsLeft < this.message.length / 10){
       alert("Not enough fuel to send " +
       "the current message!");
     }

     else {
       this.lightFire();
       var x = this.message.length;
       for(var i = 0; i < x; i++){
         alert("(((" + this.message[i] + ")))");
         if (i % 10 === 0 && i !== 0){
           this.logsLeft--;
         }
       }
     }
   }

 };

 fireOne.addLogs(8);

Answer 1

问题是你的代码的顺序。您可以在创建后添加内容。如果您在创建火焰之前添加原型(prototype)，它将起作用。

function SignalFire(ID, startingLogs){
   this.fireID = ID;
   this.logsLeft = startingLogs;
 }

 SignalFire.prototype = {
    addLogs: function(numLogs){
     this.logsLeft += numLogs;
     console.log(this.logsLeft);
   }
 };

 var fireOne = new SignalFire(1, 20);
 fireOne.addLogs(8);