Question

我无法理解为什么我的控制台给了我这个：
Uncaught TypeError: Cannot read property 'jan' of undefined

此代码的功能是将var设置为0，如果它是“未定义”。

//Set months to loop/look for
var months = ["jan","feb","mar","apr","maj","jun","jul","aug","sep","okt","nov","dec"];

//GUL Loop threw result and create vars for each month
months.forEach(function (m){
  if (! result.GulAvformning[m]) {
    result.GulAvformning[m] = {};
    result.GulAvformning[m] = 0;
  }
});

我有其他代码，并没有抱怨这个：

//BLÅ Loop threw result and create vars for each month
months.forEach(function (m){
  if (! result.BlåAvformning[m]) { console.log(result.BlåAvformning.jan);
    result.BlåAvformning[m] = {};
    result.BlåAvformning[m] = 0; console.log(result.BlåAvformning.jan);
  }
});

console.log的结果是：
undefined
0

我缺少什么？

Answer 1

不要认为您正在显示弹出result对象的相关代码。

假设result对象应该填充在这里

months.forEach(function (m){
  if ( !result )
  {
    result = {};
  }
  if ( !result.GulAvformning )
  {
     result.GulAvformning = {};
  }
  if (! result.GulAvformning[m]) {
    result.GulAvformning[m] = 0;
  }
});

无法读取未定义的属性'jan'

1 个答案: