<template>

  <div id="watch-example">

    <p>

        Ask a yes/no question:

        <input v-model="question">

    </p>

    <p>{{ answer }}</p>

  </div>

</template>

<script>

import _ from 'lodash'

import axios from 'axios'  

export default{

  data(){

    return {

      question: '',

      answer: 'I cannot give you an answer until you ask a question!'

    }

  },

  watch: {

    // 如果 `question` 发生改变，这个函数就会运行

    question: function (newQuestion, oldQuestion) {

      this.answer = 'Waiting for you to stop typing...'

      this.debouncedGetAnswer()

    }

  },

  created: function () {

    // `_.debounce` 是一个通过 Lodash 限制操作频率的函数。

    // 在这个例子中，我们希望限制访问 yesno.wtf/api 的频率

    // AJAX 请求直到用户输入完毕才会发出。想要了解更多关于

    // `_.debounce` 函数 (及其近亲 `_.throttle`) 的知识，

    // 请参考：https://lodash.com/docs#debounce

    this.debouncedGetAnswer = _.debounce(this.getAnswer, 500)

  },

  methods: {

    getAnswer: function () {

      if (this.question.indexOf('?') === -1) {

        this.answer = 'Questions usually contain a question mark. ;-)'

        return

      }

      this.answer = 'Thinking...'

      var vm = this

      axios.get('https://yesno.wtf/api')

        .then(function (response) {

          vm.answer = _.capitalize(response.data.answer)

        })

        .catch(function (error) {

          vm.answer = 'Error! Could not reach the API. ' + error

        })

    }

  }

}

</script>