在 加载数据 章节中，我们了解了如何将数据从服务器传输到浏览器。有时你需要以相反的方向发送数据，这就是 <form>（Web 平台提交数据的方式）的用武之地。

¥In the chapter on loading data, we saw how to get data from the server to the browser. Sometimes you need to send data in the opposite direction, and that’s where <form> — the web platform’s way of submitting data — comes in.

让我们构建一个待办事项应用。我们已经在 src/lib/server/database.js 中设置了一个内存数据库，并且我们在 src/routes/+page.server.js 中的 load 函数使用 cookies API，以便我们可以拥有每个用户的待办事项列表，但我们需要添加 <form> 来创建新的待办事项：

¥Let’s build a todo app. We’ve already got an in-memory database set up in src/lib/server/database.js, and our load function in src/routes/+page.server.js uses the cookies API so that we can have a per-user todo list, but we need to add a <form> to create new todos:

<h1>todos</h1>

<form method="POST">
	<label>
		add a todo:
		<input
			name="description"
			autocomplete="off"
		/>
	</label>
</form>

<ul class="todos">

如果我们在 <input> 中输入一些内容并按 Enter，浏览器会向当前页面发出 POST 请求（因为 method="POST" 属性）。但这会导致错误，因为我们尚未创建服务器端操作来处理 POST 请求。我们现在就这么做：

¥If we type something into the <input> and hit Enter, the browser makes a POST request (because of the method="POST" attribute) to the current page. But that results in an error, because we haven’t created a server-side action to handle the POST request. Let’s do that now:

import * as db from '$lib/server/database.js';

export function load({ cookies }) {
	// ...
}

export const actions = {
	default: async ({ cookies, request }) => {
		const data = await request.formData();
		db.createTodo(cookies.get('userid'), data.get('description'));
	}
};

request 是标准 请求 对象；await request.formData() 返回一个 FormData 实例。

¥The request is a standard Request object; await request.formData() returns a FormData instance.

当我们按下 Enter 键时，数据库会更新，页面会重新加载新数据。

¥When we hit Enter, the database is updated and the page reloads with the new data.

请注意，我们不必编写任何 fetch 代码或类似的东西 — 数据会自动更新。因为我们使用的是 <form> 元素，所以即使 JavaScript 被禁用或不可用，此应用也能正常运行。

¥Notice that we haven’t had to write any fetch code or anything like that — data updates automatically. And because we’re using a <form> element, this app would work even if JavaScript was disabled or unavailable.