声明式渲染

文本插值，模板语法：

<div id="counter">
  Counter: {{ counter }}
</div>

const Counter = {
  data() {
    return {
      counter: 0
    }
  }
}

Vue.createApp(Counter).mount('#counter')

const CounterApp = {
  data() {
    return {
      counter: 0
    }
  },
  mounted() {
    setInterval(() => {
      this.counter++
    }, 1000)
  }
}

绑定元素属性：

<div id="bind-attribute">
  <span v-bind:title="message">
    Hover your mouse over me for a few seconds to see my dynamically bound
    title!
  </span>
</div>

const AttributeBinding = {
  data() {
    return {
      message: 'You loaded this page on ' + new Date().toLocaleString()
    }
  }
}

Vue.createApp(AttributeBinding).mount('#bind-attribute')

处理用户输入

v-on指令，事件侦听：

<div id="event-handling">
  <p>{{ message }}</p>
  <button v-on:click="reverseMessage">Reverse Message</button>
</div>

const EventHandling = {
  data() {
    return {
      message: 'Hello Vue.js!'
    }
  },
  methods: {
    reverseMessage() {
      this.message = this.message
        .split('')
        .reverse()
        .join('')
    }
  }
}

Vue.createApp(EventHandling).mount('#event-handling')

v-model指令，双向绑定：

<div id="two-way-binding">
  <p>{{ message }}</p>
  <input v-model="message" />
</div>

const TwoWayBinding = {
  data() {
    return {
      message: 'Hello Vue!'
    }
  }
}

Vue.createApp(TwoWayBinding).mount('#two-way-binding')

条件和循环

v-if指令，切换元素的存在：

<div id="conditional-rendering">
  <span v-if="seen">Now you see me</span>
</div>

const ConditionalRendering = {
  data() {
    return {
      seen: true
    }
  }
}

Vue.createApp(ConditionalRendering).mount('#conditional-rendering')

v-for指令，循环元素：

<div id="list-rendering">
  <ol>
    <li v-for="todo in todos">
      {{ todo.text }}
    </li>
  </ol>
</div>

const ListRendering = {
  data() {
    return {
      todos: [
        { text: 'Learn JavaScript' },
        { text: 'Learn Vue' },
        { text: 'Build something awesome' }
      ]
    }
  }
}

Vue.createApp(ListRendering).mount('#list-rendering')

组成组件

注册组件：

// Create Vue application
const app = Vue.createApp(...)

// Define a new component called todo-item
app.component('todo-item', {
  template: `<li>This is a todo</li>`
})

// Mount Vue application
app.mount(...)

使用：

<ol>
  <!-- Create an instance of the todo-item component -->
  <todo-item></todo-item>
</ol>

属性：

app.component('todo-item', {
  props: ['todo'],
  template: `<li>{{ todo.text }}</li>`
})

使用：

<div id="todo-list-app">
  <ol>
    <!--
      Now we provide each todo-item with the todo object
      it's representing, so that its content can be dynamic.
      We also need to provide each component with a "key",
      which will be explained later.
    -->
    <todo-item
      v-for="item in groceryList"
      v-bind:todo="item"
      v-bind:key="item.id"
    ></todo-item>
  </ol>
</div>

const TodoList = {
  data() {
    return {
      groceryList: [
        { id: 0, text: 'Vegetables' },
        { id: 1, text: 'Cheese' },
        { id: 2, text: 'Whatever else humans are supposed to eat' }
      ]
    }
  }
}

const app = Vue.createApp(TodoList)

app.component('todo-item', {
  props: ['todo'],
  template: `<li>{{ todo.text }}</li>`
})

app.mount('#todo-list-app')