Question

我有这个代码，允许我返回一个关于连接到特定帖子的帖子的字符串。我试图在列表部分（list=list+this["connectionsTo"[i]].postNum+"\n";）中访问下面的属性时使用括号和点表示法，但不起作用。但是当我使用双点符号时，它有效，为什么？我相信那两个是一样的。

function Fencepost(x, y, postNum) {
  this.x = x;
  this.y = y;
  this.postNum = postNum;
  this.connectionsTo = [];
}

Fencepost.prototype = {
  sendRopeTo: function(connectedPost) {
    this.connectionsTo.push(connectedPost);
  },
  removeRope: function(removeTo) {
    var temp = [];
    for (var i = 0; i < this.connectionsTo.length; i++) {
      if (this.connectionsTo[i].postNum != removeTo) {
        temp.push(this.connectionsTo[i]);
      }
    }
    this.connectionsTo = temp;
  },
  movePost: function(x, y) {
    this.x = x;
    this.y = y;
  },
  valueOf: function() {
  return Math.sqrt(this.x * this.x +
                   this.y * this.y);
  }
};

Fencepost.prototype.toString=function(){
var list="";
for(var i=0;i<this.connectionsTo.length;i++){
list=list+this["connectionsTo"[i]].postNum+"\n";
}
  return "Fence post #"+this.postNum+":\nConnected to posts:\n"+list+"Distance from ranch: "+this.valueOf()+" yards";
};

var post10=new Fencepost(3,4,10);
var post11=new Fencepost(5,7,11);
var post12=new Fencepost(6,7,12);
var post13=new Fencepost(8,9,13);
post10.sendRopeTo(post11);
post10.sendRopeTo(post12);
post10.sendRopeTo(post13);
console.log(post10.toString());

Answer 1

由于您正在迭代this.connectionsTo数组，因此您正在寻找

this["connectionsTo"][i]

或the equivalent

this.connectionsTo[i]

而不是

this["connectionsTo"[i]]

为字符串编制索引，然后将该字符作为this的属性。

Javascript原型覆盖

1 个答案: