Udacity谋杀谜题：JavaScript变量无法保存值问题求助

AI 小北

2026-5-27

问题分析与解决

嘿，我一眼就揪出问题所在啦！这是新手常踩的小坑——你把赋值运算符和全等比较运算符搞混了😅

核心错误点

在JavaScript里：

= 是赋值运算符，用来给变量设置新值（比如 weapon = "pool stick"）
=== 是全等比较运算符，用来判断两个值是否完全相等（比如 room === "ballroom"）

你代码里所有给weapon和solved赋值的地方都用了===，这相当于在做“判断变量是否等于某个值”的操作，而非真正给变量赋值。所以不管条件满足与否，weapon始终是初始的空字符串，solved也一直是初始的true，自然没法输出正确结果。

修正后的代码

var room = "ballroom"; 
var suspect = "Mr. Kalehoff"; 
var weapon = ""; 
var solved = true; 

if (room === "dining room" && suspect === "Mr. Parkes") { 
  weapon = "knife"; 
  solved = true; 
} else if (room === "gallery") { 
  weapon = "trophy"; 
  solved = true; 
} else if (room === "ballroom" && suspect === "Mr. Kalehoff") { 
  weapon = "pool stick"; 
  solved = true; 
} else { 
  weapon = "poison"; 
  solved = false; 
} 

if (solved) { 
  console.log(suspect + " did it in the " + room + " with the " + weapon + "!"); 
}