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从0开始手把手教你用Vue开发一个答题App01之项目创建及答题设置页面开发

项目演示

项目演示

项目源码

项目源码

配套讲解视频

配套讲解视频

教程说明

本教程适合对 Vue 基础知识有一点了解,但不懂得综合运用,还未曾使用 Vue 从头开发过一个小型 App 的读者。本教程不对所有的 Vue 知识点进行讲解,而是手把手一步步从 0 到 1,做出一个完整的小项目。目前网上的教程不是只有零散的知识点讲解;就是抛出一个开源的大项目,初级读者下载下来后,运行起来都很费劲,更谈不上理解这个项目是如何一步步开发出来的了。本教程试图弥补这个空白。

1. 项目初始化

1.1 使用 Vue CLI 创建项目

如果你还没有安装 VueCLI,请执行下面的命令安装或是升级:

npm install --global @vue/cli

在命令行中输入以下命令创建 Vue 项目:

vue create vue-quiz
Vue CLI v4.3.1
? Please pick a preset:
> default (babel, eslint)
  Manually select features

default:默认勾选 babel、eslint,回车之后直接进入装包

manually:自定义勾选特性配置,选择完毕之后,才会进入装包

选择第 1 种 default.

安装结束,命令提示你项目创建成功,按照命令行的提示在终端中分别输入:

# 进入你的项目目录
cd vue-quiz

# 启动开发服务
npm run serve

启动成功,命令行中输出项目的 http 访问地址。打开浏览器,输入其中任何一个地址进行访问

如果能看到该页面,恭喜你,项目创建成功了。

1.2 初始目录结构

项目创建好以后,下面我们来了解一下初始目录结构:

1.3 调整初始目录结构,实现游戏设置页面

默认生成的目录结构不满足我们的开发需求,所以需要做一些自定义改动。

这里主要处理下面的内容:

  • 删除初始化的默认文件
  • 新增调整我们需要的目录结构

删除默认示例文件:

  • src/components/HelloWorld.vue
  • src/assets/logo.png

修改 package.json,添加项目依赖:

 "dependencies": {
    "axios": "^0.19.2",
    "bootstrap": "^4.4.1",
    "bootstrap-vue": "^2.5.0",
    "core-js": "^3.6.5",
    "vue": "^2.6.11",
    "vue-router": "^3.1.5"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "~4.4.0",
    "@vue/cli-plugin-eslint": "~4.4.0",
    "@vue/cli-plugin-router": "~4.4.0",
    "@vue/cli-service": "~4.4.0",
    "babel-eslint": "^10.1.0",
    "eslint": "^6.7.2",
    "eslint-plugin-vue": "^6.2.2",
    "vue-template-compiler": "^2.6.11"
  },

然后运行 yarn install, 安装依赖。

修改项目入口文件 main.js,引入 bootstrap-vue。

import Vue from 'vue'
import App from './App.vue'
import router from './router'
import BootstrapVue from 'bootstrap-vue'
import 'bootstrap/dist/css/bootstrap.css'
import 'bootstrap-vue/dist/bootstrap-vue.css'

Vue.config.productionTip = false

Vue.use(BootstrapVue)

const state = {questions: [] }

new Vue({
  router,
  data: state,
  render: h => h(App)
}).$mount('#app')

定义一个 state 对象来共享答题数据(答题页面和结果页面共享)

const state = {questions: [] }

src 目录下新增 eventBus.js 消息总线,用来在组件间传递消息,代码如下:

import Vue from 'vue'
const EventBus = new Vue()
export default EventBus

修改 App.vue,css 样式略,请参考源码。

<template>
  <div id="app" class="bg-light">
    <Navbar></Navbar>
    <b-alert :show="dismissCountdown" dismissible variant="danger" @dismissed="dismissCountdown = 0">
      {{errorMessage}}
    </b-alert>
    <div class="d-flex justify-content-center">
      <b-card no-body id="main-card" class="col-sm-12 col-lg-4 px-0">
        <router-view></router-view>
      </b-card>
    </div>
  </div>
</template>

<script>
import EventBus from './eventBus'
import Navbar from './components/Navbar'

export default {
  name: 'app',
  components: {Navbar},
  data() {
    return {
      errorMessage: '',
      dismissSecs: 5,
      dismissCountdown: 0
    }
  },
  methods: {showAlert(error) {
      this.errorMessage = error
      this.dismissCountdown = this.dismissSecs
    }
  },
  mounted() {EventBus.$on('alert-error', (error) => {this.showAlert(error)
    })
  },
  beforeDestroy() {EventBus.$off('alert-error')
  }
}
</script>

新增 components/Navbar.vue,定义导航部分。

<template>
    <b-navbar id="navbar" class="custom-info" type="dark" sticky>
      <b-navbar-brand id="nav-logo" :to="{name:'home'}">Vue-Quiz</b-navbar-brand>

      <b-navbar-nav class="ml-auto">
        <b-nav-item :to="{name:'home'}">New Game </b-nav-item>
        <b-nav-item href="#" target="_blank">About</b-nav-item>
      </b-navbar-nav>
    </b-navbar>
</template>

<script>
export default {name: 'Navbar'}
</script>

<style scoped>

</style>

src 目录下新增 router/index.js,定义首页路由。

import Vue from 'vue'
import VueRouter from 'vue-router'
import MainMenu from '../views/MainMenu.vue'


Vue.use(VueRouter)

const routes = [
  {
    name: 'home',
    path: '/',
    component: MainMenu
  }
]

const router = new VueRouter({
  mode: 'history',
  base: process.env.BASE_URL,
  routes
})

export default router

src 下新增 views/MainMenu.vue,MainMenu 主要包含 GameForm 组件。

<template>
<div>
  <b-card-header class="custom-info text-white font-weight-bold">New Game</b-card-header>
  <b-card-body class="h-100">
    <GameForm @form-submitted="handleFormSubmitted"></GameForm>
  </b-card-body>
</div>
</template>

<script>
import GameForm from '../components/GameForm'

export default {
  name: 'MainMenu',
  components: {GameForm},
  methods: {
    /** Triggered by custom 'form-submitted' event from GameForm child component. 
     * Parses formData, and route pushes to 'quiz' with formData as query
     * @public
     */
    handleFormSubmitted(formData) {
      const query = formData
      query.difficulty = query.difficulty.toLowerCase()
      this.$router.push({name: 'quiz', query: query})
    }
  }
}
</script>

新增 src/components/GameForm.vue,实现游戏初始设置。

<template>
  <div>
    <LoadingIcon v-if="loading"></LoadingIcon>

    <div v-else>
      <b-form @submit="onSubmit">
        <b-form-group 
          id="input-group-number-of-questions"
          label="Select a number"
          label-for="input-number-of-questions"
          class="text-left"
        >
          <b-form-input
            id="input-number-of-questions"
            v-model="form.number"
            type="number"
            :min="minQuestions"
            :max="maxQuestions"
            required 
            :placeholder="`Between ${minQuestions} and ${maxQuestions}`"
          ></b-form-input>
        </b-form-group>

        <b-form-group id="input-group-category">
          <b-form-select
            id="input-category"
            v-model="form.category"
            :options="categories"
          ></b-form-select>
        </b-form-group>

        <b-form-group id="input-group-difficulty">
          <b-form-select
            id="input-difficulty"
            v-model="form.difficulty"
            :options="difficulties"
          ></b-form-select>
        </b-form-group>

        <b-form-group id="input-group-type">
          <b-form-select
            id="input-type"
            v-model="form.type"
            :options="types"
          ></b-form-select>
        </b-form-group>

        <b-button type="submit" class="custom-success">Submit</b-button>
      </b-form>
    </div>
  </div>
</template>

<script>
import LoadingIcon from './LoadingIcon'
import axios from 'axios'

export default {
  components: {LoadingIcon},
  data() {
    return {
      // Form data, tied to respective inputs
      form: {
        number: '',
        category: '',
        difficulty: '',
        type: ''
      },
      // Used for form dropdowns and number input
      categories: [{text: 'Category', value: ''}],
      difficulties: [{text: 'Difficulty', value: ''},'Easy','Medium','Hard'],
      types: [{ text: 'Type', value: ''}, 
        {text: 'Multiple Choice', value: 'multiple'}, 
        {text: 'True or False', value: 'boolean'}
      ],
      minQuestions: 10,
      maxQuestions: 20,
      // Used for displaying ajax loading animation OR form
      loading: true
    }
  },
  created() {this.fetchCategories()
  },
  methods: {fetchCategories() {axios.get('https://opentdb.com/api_category.php')
      .then(resp => resp.data)
      .then(resp => {
        resp.trivia_categories.forEach(category => {this.categories.push({text: category.name, value: `${category.id}`})
        });
        this.loading = false;
      })
    },
    onSubmit(evt) {evt.preventDefault()
       /** Triggered on form submit. Passes form data
        * @event form-submitted
        * @type {number|string}
        * @property {object}
        */
      this.$emit('form-submitted', this.form)
    }
  }
}
</script>

GameForm 组件,主要通过 axios 发起获取全部题目分类请求:

axios.get('https://opentdb.com/api_category.php')

新增 src/components/LoadingIcon.vue,在异步请求数据未返回时,渲染等待图标。

<template>
  <div id="loading-icon" class="h-100 d-flex justify-content-center align-items-center">
    <img src="@/assets/ajax-loader.gif" alt="Loading Icon">
  </div>
</template>

<script>
export default {name: 'LoadingIcon'}
</script>

新增 src/assets/ajax-loader.gif 等待动画文件,请参考项目源码。

1.4 运行项目

yarn run serve

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