Cannot use ‘in’ operator to search for ‘letters’ in undefined

Question

vue.esm.js?efeb:4794 Uncaught TypeError: Cannot use ‘in’ operator to search for ‘letters’ in undefined

这个报错怎么解决，想问

Answer 1

Dell 2019-11-24 15:49:30

我看你代码，哪里用了 in 这个语句？

• 提问者 慕村5606267 #1

  Alphabet.vue文件中适用了in
   computed: {
      letters() {
        let letters = []
        for (let i in this.cities) {
          letters.push(i)
          conosle.log(i)
        }
        return lthis.cities
       
      }
    }

• Dell #2

  for  in用于遍历数组或对象，看是不是cites格式不对