响应式
声明状态
更新状态
计算属性
<script>
let count = $state(10);
const doubleCount = $derived(count * 2);
</script>
<div>{doubleCount}</div>
模板语法
最简模板
样式
<h1 class="title">我是红色的</h1>
<button style="font-size: 10rem;">我是一个按钮</button>
<style>
.title {
color: red;
}
</style>
DOM循环
<script>
const colors = ["红", "绿", "蓝"];
</script>
<ul>
{#each colors as color (color)}
<li>{color}</li>
{/each}
</ul>
点击事件
<script>
let count = $state(0);
function incrementCount() {
count++;
}
</script>
<p>计数器: {count}</p>
<button onclick={incrementCount}>+1</button>
DOM引用
<script>
let inputElement;
$effect(() => {
inputElement.focus();
});
</script>
<input bind:this={inputElement} />
条件渲染
<script>
const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
let lightIndex = $state(0);
const light = $derived(TRAFFIC_LIGHTS[lightIndex]);
function nextLight() {
lightIndex = (lightIndex + 1) % TRAFFIC_LIGHTS.length;
}
</script>
<button onclick={nextLight}>下一个灯</button>
<p>现在亮着的是: {light}</p>
<p>
你应该
{#if light === "红灯"}
<span>停下</span>
{:else if light === "黄灯"}
<span>慢行</span>
{:else if light === "绿灯"}
<span>赶紧走</span>
{/if}
</p>
import { createSignal, Switch, Match } from "solid-js";
const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
export default function TrafficLight() {
const [lightIndex, setLightIndex] = createSignal(0);
const light = () => TRAFFIC_LIGHTS[lightIndex()];
function nextLight() {
setLightIndex((lightIndex() + 1) % TRAFFIC_LIGHTS.length);
}
return (
<>
<button onClick={nextLight}>下一个灯</button>
<p>现在亮着的是: {light()}</p>
<p>
你应该
<Switch>
<Match when={light() === "红灯"}>
<span>停下</span>
</Match>
<Match when={light() === "黄灯"}>
<span>慢行</span>
</Match>
<Match when={light() === "绿灯"}>
<span>赶紧走</span>
</Match>
</Switch>
</p>
</>
);
}
生命周期
组件加载时
<script>
let pageTitle = $state("");
$effect(() => {
pageTitle = document.title;
});
</script>
<p>页面标题: {pageTitle}</p>
组件卸载时
<script>
let time = $state(new Date().toLocaleTimeString());
$effect(() => {
const timer = setInterval(() => {
time = new Date().toLocaleTimeString();
}, 1000);
return () => clearInterval(timer);
});
</script>
<p>当前时间: {time}</p>
import { createSignal, onCleanup } from "solid-js";
export default function Time() {
const [time, setTime] = createSignal(new Date().toLocaleTimeString());
const timer = setInterval(() => {
setTime(new Date().toLocaleTimeString());
}, 1000);
onCleanup(() => clearInterval(timer));
return <p>当前时间: {time()}</p>;
}
组件组合
组件Props传参
<script>
import UserProfile from "./UserProfile.svelte";
</script>
<UserProfile
name="张三"
age={20}
favouriteColors={["green", "blue", "red"]}
isAvailable
/>
向父组件emit事件
<script>
import AnswerButton from "./AnswerButton.svelte";
let isHappy = $state(true);
function onAnswerNo() {
isHappy = false;
}
function onAnswerYes() {
isHappy = true;
}
</script>
<p>你快乐吗?</p>
<AnswerButton onYes={onAnswerYes} onNo={onAnswerNo} />
<p style="font-size: 50px;">{isHappy ? "😀" : "😥"}</p>
import { createSignal } from "solid-js";
import AnswerButton from "./AnswerButton.jsx";
export default function App() {
const [isHappy, setIsHappy] = createSignal(true);
function onAnswerNo() {
setIsHappy(false);
}
function onAnswerYes() {
setIsHappy(true);
}
return (
<>
<p>你快乐吗?</p>
<AnswerButton onYes={onAnswerYes} onNo={onAnswerNo} />
<p style={{ "font-size": "50px" }}>{isHappy() ? "😀" : "😥"}</p>
</>
);
}
slot插槽
slot插槽内容
上下文
<script>
import { setContext } from "svelte";
import UserProfile from "./UserProfile.svelte";
import createUserState from "./createUserState.svelte.js";
const user = createUserState({
id: 1,
username: "abcdefg",
email: "[email protected]",
});
setContext("user", user);
</script>
<h1>欢迎回来, {user.username}</h1>
<UserProfile />
import { createSignal } from "solid-js";
import { UserContext } from "./UserContext";
import UserProfile from "./UserProfile";
export default function App() {
const [user, setUser] = createSignal({
id: 1,
username: "abcdefg",
email: "[email protected]",
});
function updateUsername(newUsername) {
setUser({ ...user(), username: newUsername });
}
return (
<>
<h1>欢迎回来, {user().username}</h1>
<UserContext.Provider value={[user, updateUsername]}>
<UserProfile />
</UserContext.Provider>
</>
);
}
表单输入
输入框
复选框
<script>
let isAvailable = $state(false);
</script>
<input id="is-available" type="checkbox" bind:checked={isAvailable} />
<label for="is-available">这是一个checkbox</label>
import { createSignal } from "solid-js";
export default function IsAvailable() {
const [isAvailable, setIsAvailable] = createSignal(false);
function handleChange() {
setIsAvailable((previousValue) => !previousValue);
}
return (
<>
<input
id="is-available"
type="checkbox"
checked={isAvailable()}
onChange={handleChange}
/>
<label for="is-available">这是一个checkbox</label>
</>
);
}
单选框
<script>
let picked = $state("red");
</script>
<div>你选择了: {picked}</div>
<input id="blue-pill" bind:group={picked} type="radio" value="blue" />
<label for="blue-pill">蓝色</label>
<input id="red-pill" bind:group={picked} type="radio" value="red" />
<label for="red-pill">红色</label>
import { createSignal } from "solid-js";
export default function PickPill() {
const [picked, setPicked] = createSignal("red");
function handleChange(event) {
setPicked(event.target.value);
}
return (
<>
<div>你选择了: {picked()}</div>
<input
id="blue-pill"
checked={picked() === "blue"}
type="radio"
value="blue"
onChange={handleChange}
/>
<label for="blue-pill">蓝色</label>
<input
id="red-pill"
checked={picked() === "red"}
type="radio"
value="red"
onChange={handleChange}
/>
<label for="red-pill">红色</label>
</>
);
}
选择器
<script>
let selectedColorId = $state(2);
const colors = [
{ id: 1, text: "红" },
{ id: 2, text: "蓝" },
{ id: 3, text: "绿" },
{ id: 4, text: "灰", isDisabled: true },
];
</script>
<select bind:value={selectedColorId}>
{#each colors as color}
<option value={color.id} disabled={color.isDisabled}>
{color.text}
</option>
{/each}
</select>
import { createSignal, For } from "solid-js";
const colors = [
{ id: 1, text: "红" },
{ id: 2, text: "蓝" },
{ id: 3, text: "绿" },
{ id: 4, text: "灰", isDisabled: true },
];
export default function ColorSelect() {
const [selectedColorId, setSelectedColorId] = createSignal(2);
function handleChange(event) {
setSelectedColorId(event.target.value);
}
return (
<select value={selectedColorId()} onChange={handleChange}>
<For each={colors}>
{(color) => (
<option value={color.id} disabled={color.isDisabled}>
{color.text}
</option>
)}
</For>
</select>
);
}
Web应用特性
渲染应用
fetch获取数据
<script>
import useFetchUsers from "./useFetchUsers.svelte.js";
const response = useFetchUsers();
</script>
{#if response.isLoading}
<p>正在获取用户信息……</p>
{:else if response.error}
<p>获取用户信息出错</p>
{:else if response.users}
<ul>
{#each response.users as user}
<li>
<img src={user.picture.thumbnail} alt="user" />
<p>
{user.name.first}
{user.name.last}
</p>
</li>
{/each}
</ul>
{/if}
import { createResource, For, Switch, Match } from "solid-js";
async function fetchUsers() {
return (await fetch("https://randomuser.me/api/?results=3")).json();
}
export default function App() {
const [data] = createResource(fetchUsers);
const users = () => data()?.results;
return (
<Switch>
<Match when={data.loading}>
<p>正在获取用户信息……</p>
</Match>
<Match when={data.error}>
<p>获取用户信息出错</p>
</Match>
<Match when={users()}>
<ul>
<For each={users()}>
{(user) => (
<li>
<img src={user.picture.thumbnail} alt="user" />
<p>
{user.name.first} {user.name.last}
</p>
</li>
)}
</For>
</ul>
</Match>
</Switch>
);
}