响应式
声明状态
更新状态
计算属性
<script setup>
import { ref, computed } from "vue";
const count = ref(10);
const doubleCount = computed(() => count.value * 2);
</script>
<template>
<div>{{ doubleCount }}</div>
</template>
Mithril
import m from "mithril";
export default function DoubleCount() {
let count = 10;
let doubleCount = count * 2;
return {
view: () => m("div", doubleCount),
};
}
模板语法
最简模板
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>
Mithril
import "./style.css";
import m from "mithril";
export default function CssStyle() {
return {
view: () =>
m(
"div",
m("h1.title", "我是红色的"),
m("button", { style: { fontSize: "10rem" } }, "我是一个按钮"),
),
};
}
DOM循环
<script setup>
const colors = ["红", "绿", "蓝"];
</script>
<template>
<ul>
<li v-for="color in colors" :key="color">
{{ color }}
</li>
</ul>
</template>
Mithril
import m from "mithril";
export default function Colors() {
const colors = ["红", "绿", "蓝"];
return {
view: () =>
m(
"ul",
colors.map((color, idx) => m("li", { key: idx }, color)),
),
};
}
点击事件
<script setup>
import { ref } from "vue";
const count = ref(0);
function incrementCount() {
count.value++;
}
</script>
<template>
<p>计数器: {{ count }}</p>
<button @click="incrementCount">+1</button>
</template>
Mithril
import m from "mithril";
export default function Counter() {
let count = 0;
const incrementCount = () => (count = count + 1);
return {
view: () =>
m(
"div",
m("p", `计数器: ${count}`),
m("button", { onclick: incrementCount }, "+1"),
),
};
}
DOM引用
<script setup>
import { useTemplateRef, onMounted } from "vue";
const inputElement = useTemplateRef("inputElement");
onMounted(() => {
inputElement.value.focus();
});
</script>
<template>
<input ref="inputElement" />
</template>
Mithril
import m from "mithril";
export default function InputFocused() {
let value = "";
return {
view: () =>
m("input", {
oncreate: ({ dom }) => dom.focus(),
type: "text",
value,
oninput: (e) => (value = e.target.value),
}),
};
}
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>
Mithril
import m from "mithril";
const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
export default function TrafficLight() {
let lightIndex = 0;
let currentLight = () => TRAFFIC_LIGHTS[lightIndex];
const nextLight = () => (lightIndex + 1) % TRAFFIC_LIGHTS.length;
const instructions = () => {
switch (currentLight()) {
case "红灯":
return "停下";
case "黄灯":
return "慢行";
case "绿灯":
return "赶紧走";
}
};
return {
view: () =>
m(
"div",
m("button", { onclick: nextLight }, "下一个灯"),
m("p", `现在亮着的是: ${currentLight()}`),
m("p", "你应该 ", m("span", instructions())),
),
};
}
生命周期
组件加载时
<script setup>
import { ref, onMounted } from "vue";
const pageTitle = ref("");
onMounted(() => {
pageTitle.value = document.title;
});
</script>
<template>
<p>页面标题: {{ pageTitle }}</p>
</template>
Mithril
import m from "mithril";
export default function PageTitle() {
return {
view: () => m("p", `页面标题: ${document.title}`),
};
}
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>
Mithril
import m from "mithril";
export default function Time() {
let time = new Date().toLocaleTimeString();
const timer = setInterval(() => {
time = new Date().toLocaleTimeString();
m.redraw();
}, 1000);
return {
view: () => m("p", `当前时间: ${time}`),
onremove: () => clearInterval(timer),
};
}
组件组合
组件Props传参
<script setup>
import UserProfile from "./UserProfile.vue";
</script>
<template>
<UserProfile
name="张三"
:age="20"
:favourite-colors="['green', 'blue', 'red']"
is-available
/>
</template>
Mithril
import m from "mithril";
import UserProfile from "./UserProfile.js";
export default function App() {
return {
view: () =>
m(UserProfile, {
name: "张三",
age: 20,
favouriteColors: ["green", "blue", "red"],
isAvailable: true,
}),
};
}
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>
Mithril
import m from "mithril";
export const AnswerButton = ({ attrs: { onYes, onNo } }) => ({
view: () =>
m(
"div",
m("button", { onclick: onYes }, "是的!"),
m("button", { onclick: onNo }, "不是!"),
),
});
slot插槽
slot插槽内容
<script setup>
import FunnyButton from "./FunnyButton.vue";
</script>
<template>
<FunnyButton />
<FunnyButton> 这是传到slot的内容! </FunnyButton>
</template>
Mithril
import m from "mithril";
import FunnyButton from "./FunnyButton.jsx";
export default function App() {
return {
view: () => m("", m(FunnyButton), m(FunnyButton, "这是传到slot的内容!")),
};
}
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>
Mithril
import m from "mithril";
import UserProfile from "./UserProfile";
export default function App() {
const user = {
id: 1,
username: "abcdefg",
email: "[email protected]",
};
const updateUsername = (username) => (user.username = username);
return {
view: () =>
m(
"",
m("h1", `欢迎回来, ${user.username}`),
m(UserProfile, { user, updateUsername }),
),
};
}
表单输入
输入框
<script setup>
import { ref } from "vue";
const text = ref("你好世界");
</script>
<template>
<p>{{ text }}</p>
<input v-model="text" />
</template>
Mithril
import m from "mithril";
export default function InputHello() {
let text = "你好世界";
const handleChange = ({ target: { value } }) => (text = value);
return {
view: () =>
m("", m("p", text), m("input", { value: text, onchange: handleChange })),
};
}
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>
Mithril
import m from "mithril";
export default function IsAvailable() {
let isAvailable = false;
const onUpdate = () => (isAvailable = !isAvailable);
return {
view: () =>
m(
"",
m("input", {
id: "is-available",
type: "checkbox",
checked: isAvailable,
onchange: onUpdate,
}),
m("label", { for: "is-available" }, "这是一个checkbox"),
),
};
}
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>
Mithril
import m from "mithril";
export default function PickPill() {
let picked = "red";
let pills = ["red", "green", "blue"];
const handleChange = ({ target: { value } }) => (picked = value);
return {
view: () =>
m(
"",
m("", `你选择了: ${picked}`),
pills.map((pill) =>
m(
".",
m("input", {
id: pill,
checked: picked == pill,
type: "radio",
value: pill,
onchange: handleChange,
}),
m("label", { for: pill }, pill),
),
),
),
};
}
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>
Mithril
import m from "mithril";
const colors = [
{ id: 1, text: "红" },
{ id: 2, text: "蓝" },
{ id: 3, text: "绿" },
{ id: 4, text: "灰", isDisabled: true },
];
export default function ColorSelect() {
let selectedColorId = 2;
const handleSelect = ({ target: { value } }) => (selectedColorId = value);
return {
view: () =>
m(
"select",
{ value: selectedColorId, onchange: handleSelect },
colors.map(({ id, text, isDisabled }) =>
m("option", { key: id, id, disabled: isDisabled, value: id }, text),
),
),
};
}
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>
Mithril
import m from "mithril";
export default function App() {
let isLoading = false;
let error = null;
let users = [];
async function fetchUsers() {
isLoading = true;
try {
const { results } = await m.request(
"https://randomuser.me/api/?results=3",
);
users = results;
} catch (err) {
error = err;
}
isLoading = false;
}
return {
oninit: fetchUsers,
view() {
if (isLoading) return m("p", "正在获取用户信息……");
if (error) return m("p", "获取用户信息出错");
return users.map((user) =>
m(
"li",
{ key: user.login.uuid },
m("img", { src: user.picture.thumbnail, alt: "user" }),
m("p", `${user.name.first} ${user.name.last}`),
),
);
},
};
}