报错场景：将APi中得到的response数据，用Vue$set()使数据动态响应

报错代码：

  methods: {
    textTranslate: function (text, to) {
 
      $.ajax({
        url: 'http://openapi.youdao.com/api',
        type: 'post',
        dataType: 'jsonp',
        data: {
          q: text,
          appKey: this.appKey,
          salt: this.salt,
          from: this.from,
          to: to,
          sign: md5(this.appKey + text + this.salt + this.key)
        },
        success: function (data) {
          this.$set(this.$data, 'translatedText', data.translation[0])
        }
      })
    }
  }

报错原因：这里的this指向的不是VueModel,

解决方法1:在执行函数中定义指向Model的变量 let vm = this ,用该变量替代this

  methods: {
    textTranslate: function (text, to) {
      let vm = this
      $.ajax({
        url: 'http://openapi.youdao.com/api',
        type: 'post',
        dataType: 'jsonp',
        data: {
          q: text,
          appKey: this.appKey,
          salt: this.salt,
          from: this.from,
          to: to,
          sign: md5(this.appKey + text + this.salt + this.key)
        },
        success: function (data) {
          vm.$set(vm.$data, 'translatedText', data.translation[0])
        }
      })
    }
  }

解决方法2:将。siccess改为箭头函数的写法，这样子箭头函数里的this其实是指向VueModel的，这样子用this看不会报错了

success: (data) => {
          this.$set(this.$data, 'translatedText', data.translation[0])
        }