你还可以添加改变数据的处理程序，例如 POST。在大多数情况下，你应该改用 表单操作 — 你最终会编写更少的代码，并且它可以在没有 JavaScript 的情况下工作，从而使其更具弹性。

¥You can also add handlers that mutate data, such as POST. In most cases, you should use form actions instead — you’ll end up writing less code, and it’ll work without JavaScript, making it more resilient.

在 ‘添加待办事项’ <input> 的 keydown 事件处理程序中，让我们将一些数据发布到服务器：

¥Inside the keydown event handler of the ‘add a todo’ <input>, let’s post some data to the server:

<input
	type="text"
	autocomplete="off"
	onkeydown={async (e) => {
		if (e.key !== 'Enter') return;

		const input = e.currentTarget;
		const description = input.value;

		const response = await fetch('/todo', {
			method: 'POST',
			body: JSON.stringify({ description }),
			headers: {
				'Content-Type': 'application/json'
			}
		});

		input.value = '';
	}}
/>

在这里，我们将一些 JSON 发布到 /todo API 路由 — 使用来自用户 cookie 的 userid — 并接收新创建的待办事项的 id 作为响应。

¥Here, we’re posting some JSON to the /todo API route — using a userid from the user’s cookies — and receiving the id of the newly created todo in response.

通过添加带有 POST 处理程序的 src/routes/todo/+server.js 文件来创建 /todo 路由，该处理程序在 src/lib/server/database.js 中调用 createTodo：

¥Create the /todo route by adding a src/routes/todo/+server.js file with a POST handler that calls createTodo in src/lib/server/database.js:

import { json } from '@sveltejs/kit';
import * as database from '$lib/server/database.js';

export async function POST({ request, cookies }) {
	const { description } = await request.json();

	const userid = cookies.get('userid');
	const { id } = await database.createTodo({ userid, description });

	return json({ id }, { status: 201 });
}

与 load 函数和表单操作一样，request 是一个标准的 请求 对象；await request.json() 返回我们从事件处理程序发布的数据。

¥As with load functions and form actions, the request is a standard Request object; await request.json() returns the data that we posted from the event handler.

我们返回一个带有 201 已创建 状态和数据库中新生成的待办事项的 id 的响应。回到事件处理程序中，我们可以使用它来更新页面：

¥We’re returning a response with a 201 Created status and the id of the newly generated todo in our database. Back in the event handler, we can use this to update the page:

<input
	type="text"
	autocomplete="off"
	onkeydown={async (e) => {
		if (e.key !== 'Enter') return;

		const input = e.currentTarget;
		const description = input.value;

		const response = await fetch('/todo', {
			method: 'POST',
			body: JSON.stringify({ description }),
			headers: {
				'Content-Type': 'application/json'
			}
		});

		const { id } = await response.json();

		const todos = [...data.todos, {
			id,
			description
		}];

		data = { ...data, todos };

		input.value = '';
	}}
/>

你只能以这样的方式更新 data，即通过重新加载页面获得相同的结果。data prop 不是深度响应式的，因此你需要替换它 - 像 data.todos = todos 这样的突变不会导致重新渲染。

¥[!NOTE] You should only update data in such a way that you’d get the same result by reloading the page. The data prop is not deeply reactive, so you need to replace it — mutations like data.todos = todos will not cause a re-render.