响应式
声明状态
更新状态
模板语法
样式
<template>
<h1 class="title">我是红色的</h1>
<button style="font-size: 10rem">我是一个按钮</button>
</template>
<style scoped>
.title {
color: red;
}
</style>
DOM循环
点击事件
DOM引用
<script setup>
import { useTemplateRef, onMounted } from "vue";
const inputElement = useTemplateRef("inputElement");
onMounted(() => {
inputElement.value.focus();
});
</script>
<template>
<input ref="inputElement" />
</template>
条件渲染
<script setup>
import { ref, computed } from "vue";
const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
const lightIndex = ref(0);
const light = computed(() => TRAFFIC_LIGHTS[lightIndex.value]);
function nextLight() {
lightIndex.value = (lightIndex.value + 1) % TRAFFIC_LIGHTS.length;
}
</script>
<template>
<button @click="nextLight">下一个灯</button>
<p>现在亮着的是: {{ light }}</p>
<p>
你应该
<span v-if="light === '红灯'">停下</span>
<span v-else-if="light === '黄灯'">慢行</span>
<span v-else-if="light === '绿灯'">赶紧走</span>
</p>
</template>
static const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
<let/lightIndex=0>
<const/light=TRAFFIC_LIGHTS[lightIndex]>
<button onClick() { lightIndex = (lightIndex + 1) % TRAFFIC_LIGHTS.length }>
下一个灯
</button>
<p>现在亮着的是: ${light}</p>
<p>
你应该
<if=light === "红灯">停下</if>
<else if=light === "黄灯">慢行</else>
<else>赶紧走</else>
</p>
生命周期
组件加载时
组件卸载时
<script setup>
import { ref, onUnmounted } from "vue";
const time = ref(new Date().toLocaleTimeString());
const timer = setInterval(() => {
time.value = new Date().toLocaleTimeString();
}, 1000);
onUnmounted(() => {
clearInterval(timer);
});
</script>
<template>
<p>当前时间: {{ time }}</p>
</template>
组件组合
组件Props传参
向父组件emit事件
<script setup>
import { ref } from "vue";
import AnswerButton from "./AnswerButton.vue";
let isHappy = ref(true);
function onAnswerNo() {
isHappy.value = false;
}
function onAnswerYes() {
isHappy.value = true;
}
</script>
<template>
<p>你快乐吗?</p>
<AnswerButton @yes="onAnswerYes" @no="onAnswerNo" />
<p style="font-size: 50px">
{{ isHappy ? "😀" : "😥" }}
</p>
</template>
slot插槽
slot插槽内容
上下文
<script setup>
import { ref, provide } from "vue";
import UserProfile from "./UserProfile.vue";
const user = ref({
id: 1,
username: "abcdefg",
email: "[email protected]",
});
function updateUsername(username) {
user.value.username = username;
}
provide("user", { user, updateUsername });
</script>
<template>
<h1>欢迎回来, {{ user.username }}</h1>
<UserProfile />
</template>
<let/user={
id: 1,
username: "abcdefg",
email: "[email protected]",
}>
<const/updateUsername(newUsername) {
user = { ...user, username: newUsername };
}>
<h1>欢迎回来, ${user.username}</h1>
<context={ ...user, updateUsername }>
<UserProfile />
</context>
表单输入
输入框
复选框
<script setup>
import { ref } from "vue";
const isAvailable = ref(true);
</script>
<template>
<input id="is-available" v-model="isAvailable" type="checkbox" />
<label for="is-available">这是一个checkbox</label>
</template>
单选框
<script setup>
import { ref } from "vue";
const picked = ref("red");
</script>
<template>
<div>你选择了: {{ picked }}</div>
<input id="blue-pill" v-model="picked" type="radio" value="blue" />
<label for="blue-pill">蓝色</label>
<input id="red-pill" v-model="picked" type="radio" value="red" />
<label for="red-pill">红色</label>
</template>
选择器
<script setup>
import { ref } from "vue";
const selectedColorId = ref(2);
const colors = [
{ id: 1, text: "红" },
{ id: 2, text: "蓝" },
{ id: 3, text: "绿" },
{ id: 4, text: "灰", isDisabled: true },
];
</script>
<template>
<select v-model="selectedColorId">
<option
v-for="color in colors"
:key="color.id"
:value="color.id"
:disabled="color.isDisabled"
>
{{ color.text }}
</option>
</select>
</template>
static const colors = [
{ id: 1, text: "红" },
{ id: 2, text: "蓝" },
{ id: 3, text: "绿" },
{ id: 4, text: "灰", isDisabled: true },
];
<let/selectedColorId=2>
<select value:=selectedColorId>
<for|{ id, isDisabled, text }| of=colors>
<option value=id disabled=isDisabled>
${text}
</option>
</for>
</select>
Web应用特性
渲染应用
fetch获取数据
<script setup>
import useFetchUsers from "./useFetchUsers";
const { isLoading, error, data: users } = useFetchUsers();
</script>
<template>
<p v-if="isLoading">正在获取用户信息……</p>
<p v-else-if="error">获取用户信息出错</p>
<ul v-else-if="users">
<li v-for="user in users" :key="user.login.uuid">
<img :src="user.picture.thumbnail" alt="user" />
<p>
{{ user.name.first }}
{{ user.name.last }}
</p>
</li>
</ul>
</template>
<try>
<await|{ results: users }|=fetch("https://randomuser.me/api/?results=3").then(res => res.json())>
<ul>
<for|{ picture, name }| of=users>
<li>
<img src=picture.thumbnail alt="user">
<p>${name.first} ${name.last}</p>
</li>
</for>
</ul>
</await>
<@placeholder>
<p>正在获取用户信息……</p>
</@placeholder>
<@catch|error|>
<p>获取用户信息出错</p>
</@catch>
</try>