Vue 報錯TypeError: this.$set is not a function 的解決方法

 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])
 }
 })
 }
 }

 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])
 }
 })
 }
 }

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