无法读取属性'0'的未定义 [英] Cannot read property '0' of undefined

问题描述

getBrand: function(brandId) {
  for(var i=0; i<malls.length; i++) {
    for(var j=0;j<malls[i].brands.length; j++){
      //console.log(malls[i][brands[j]);
      //console.log(malls[i].brands[j].id);
      if(malls.brands[j].id==(brandId)){
        console.log(malls.brands[j].id);
        return malls.brands[j].id;
      }
    }
  }
}

我需要帮助，请和我的控制台我得到这个消息：类型错误：无法读取属性'0'未定义

I need help please, and in my console i get this message:TypeError: Cannot read property '0' of undefined

推荐答案

看来你有对象的数组，每个对象都有一个品牌属性，它包含数组对象。你的第二个为循环假定商场阵列本身具有品牌财产是不正确的。由于 malls.brands 是未定义你会得到错误。

It seems you have an array of objects and each object has a brands property that contains an array of objects. Your second for loop assumes the malls array itself has brands property which is not true. As the malls.brands is undefined you get that error.

修改

if (malls.brands[j].id==(brandId)) {

到

if (malls[i].brands[j].id==(brandId)) {

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