方法调用问题

问题描述

嗨，我有一个带有方法totalLength的此类。但是，当我调用该方法时，会得到

ReferenceError：未定义totalLength。

为什么会这样？

class Streets {
constructor (length,name,size){
this.length = length;
this.name = name;
this.size = size;

}

totalLength() {
   let sum = (firstStreet.length + secondStreet.length + thirdStreet.length + 
   fourthStreet.length);
   console.log(`Total street length = ${sum}`);
   let avg = sum / allStreets.length
   console.log(`Average street length = ${avg}`);
 }

}


totalLength();

解决方法

首先需要实例化Street实例，然后才能在其上调用方法。

let street= new Streets();
street.totalLength();

好的，您会得到进一步的错误ReferenceError: firstStreet is not defined"。