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Web standards

在整个文档中，您将看到对 SvelteKit 所构建在之上的标准Web API的引用。我们不是重新发明轮子，而是使用平台，这意味着您的现有 Web 开发技能适用于 SvelteKit。相反，学习 SvelteKit 所花费的时间将帮助您在其他地方成为一名更好的 Web 开发者。

这些 API 在所有现代浏览器以及许多非浏览器环境中都可用，如 Cloudflare Workers、Deno 和 Vercel Functions。在开发过程中，以及在基于 Node 的环境（包括 AWS Lambda）的适配器中，它们通过必要的 polyfills 提供（目前是这样的——Node 正在快速增加对更多 Web 标准的支持）。

特别是，您将熟悉以下内容：

获取 API

SvelteKit 使用 fetch 从网络获取数据。它也存在于 hooks 和 服务器路由 以及浏览器中。

[注意] 在load函数、服务器钩子和API 路由中提供了一个特殊的fetch版本，用于在服务器端渲染期间直接调用端点，无需进行 HTTP 调用，同时保留凭证。（要在load之外的服务器端代码中进行凭证化的 fetch，您必须显式传递cookie和/或authorization头。）它还允许您进行相对请求，而服务器端的fetch通常需要完全限定的 URL。

除了 fetch 本身之外，Fetch API 还包括以下接口：

请求

一个 Request 实例可在 钩子 和 服务器路由 中通过 event.request 访问。它包含如 request.json() 和 request.formData() 等有用的方法，用于获取发送到端点的数据。

响应

一个 Response 实例从 await fetch(...) 和 +server.js 文件中的处理器返回。本质上，SvelteKit 应用是一个将 Request 转换为 Response 的机器。

头信息

The 头部接口允许您读取传入的 request.headers 并设置输出的 response.headers。例如，您可以像下面这样获取 request.headers，并使用 json 便利函数发送修改后的 response.headers：

src/routes/what-is-my-user-agent/+server
import { function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json } from '@sveltejs/kit';

/** @type {import('./$types').RequestHandler} */
export function 
function GET({ request }: {
    request: any;
}): Response
@type{import('./$types').RequestHandler}
GET({ request: anyrequest }) {
	// log all headers
	var console: Console
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.


The module exports two specific components:


    

  • A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
    • 

  • A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
    • 



Warning: The global console object’s methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.


Example using the global console:


console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:


const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
@seesource
console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).


const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
See util.format() for more information.


@sincev0.1.100
log(...request: anyrequest.headers);

	// create a JSON Response using a header we received
	return function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json({
		// retrieve a specific header
		userAgent: anyuserAgent: request: anyrequest.headers.get('user-agent')
	}, {
		// set a header on the response
		ResponseInit.headers?: HeadersInit | undefinedheaders: { 'x-custom-header': 'potato' }
	});
}
import { function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json } from '@sveltejs/kit';
import type { 
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
RequestHandler } from './$types';

export const const GET: RequestHandlerGET: 
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
RequestHandler = ({ request: Request
The original request object.


request }) => {
	// log all headers
	var console: Console
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.


The module exports two specific components:


    

  • A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
    • 

  • A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
    • 



Warning: The global console object’s methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.


Example using the global console:


console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:


const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
@seesource
console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).


const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
See util.format() for more information.


@sincev0.1.100
log(...request: Request
The original request object.


request.Request.headers: Headers
Returns a Headers object consisting of the headers associated with request. Note that headers added in the network layer by the user agent will not be accounted for in this object, e.g., the “Host” header.


MDN Reference


headers);

	// create a JSON Response using a header we received
	return function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json({
		// retrieve a specific header
		userAgent: string | nulluserAgent: request: Request
The original request object.


request.Request.headers: Headers
Returns a Headers object consisting of the headers associated with request. Note that headers added in the network layer by the user agent will not be accounted for in this object, e.g., the “Host” header.


MDN Reference


headers.Headers.get(name: string): string | null
MDN Reference


get('user-agent')
	}, {
		// set a header on the response
		ResponseInit.headers?: HeadersInit | undefinedheaders: { 'x-custom-header': 'potato' }
	});
};

FormData

处理 HTML 原生表单提交时，您将处理FormData对象。

src/routes/hello/+server
import { function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json } from '@sveltejs/kit';

/** @type {import('./$types').RequestHandler} */
export async function function POST(event: any): Promise<Response>
@type{import('./$types').RequestHandler}
POST(event: anyevent) {
	const const body: anybody = await event: anyevent.request.formData();

	// log all fields
	var console: Console
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.


The module exports two specific components:


    

  • A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
    • 

  • A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
    • 



Warning: The global console object’s methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.


Example using the global console:


console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:


const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
@seesource
console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).


const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
See util.format() for more information.


@sincev0.1.100
log([...const body: anybody]);

	return function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json({
		// get a specific field's value
		name: anyname: const body: anybody.get('name') ?? 'world'
	});
}
import { function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json } from '@sveltejs/kit';
import type { 
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
RequestHandler } from './$types';

export const const POST: RequestHandlerPOST: 
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
type RequestHandler = (event: Kit.RequestEvent<Record<string, any>, string | null>) => MaybePromise<Response>
RequestHandler = async (event: Kit.RequestEvent<Record<string, any>, string | null>event) => {
	const const body: FormDatabody = await event: Kit.RequestEvent<Record<string, any>, string | null>event.RequestEvent<Record<string, any>, string | null>.request: Request
The original request object.


request.Body.formData(): Promise<FormData>
MDN Reference


formData();

	// log all fields
	var console: Console
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.


The module exports two specific components:


    

  • A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
    • 

  • A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.
    • 



Warning: The global console object’s methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.


Example using the global console:


console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:


const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
@seesource
console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).


const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
See util.format() for more information.


@sincev0.1.100
log([...const body: FormDatabody]);

	return function json(data: any, init?: ResponseInit | undefined): Response
Create a JSON Response object from the supplied data.


@paramdata The value that will be serialized as JSON.
@paraminit Options such as status and headers that will be added to the response. Content-Type: application/json and Content-Length headers will be added automatically.
json({
		// get a specific field's value
		name: FormDataEntryValuename: const body: FormDatabody.FormData.get(name: string): FormDataEntryValue | null
MDN Reference


get('name') ?? 'world'
	});
};

流 API

大多数情况下，您的端点将返回完整的数据，如上面userAgent示例所示。有时，您可能需要返回一个太大而无法一次性放入内存的响应，或者以分块形式发送的响应，为此平台提供了流—— 可读流、可写流和转换流。

URL API

URL 由 URL 接口表示，该接口包括如 origin 和 pathname（以及在浏览器中，hash）等有用属性。此接口在各种地方出现——在 hooks 和 server routes 中的 event.url，在 pages 中的 page.url，在 beforeNavigate 和 afterNavigate 中的 from 和 to 等等。

URLSearchParams

无论您在哪里遇到 URL，您都可以通过url.searchParams访问查询参数，它是一个URLSearchParams的实例：URLSearchParams：

const const foo: string | nullfoo = const url: URLurl.URL.searchParams: URLSearchParams
MDN Reference


searchParams.URLSearchParams.get(name: string): string | null
Returns the first value associated to the given search parameter.


MDN Reference


get('foo');

网络加密

The Web Crypto API is made available via the crypto global. It’s used internally for Content Security Policy headers, but you can also use it for things like generating UUIDs:

const const uuid: `${string}-${string}-${string}-${string}-${string}`uuid = var crypto: Crypto
MDN Reference


crypto.Crypto.randomUUID(): `${string}-${string}-${string}-${string}-${string}`
Available only in secure contexts.


MDN Reference


randomUUID();

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