javascript - 为什么 Next.js 中间件会多次运行？

Question

我创建了一个新的 Next.js使用npx create-next-app@latest --typescript 。安装后(版本为 13.3.4 )，在不更改任何文件的情况下，我添加了新的 middleware.ts src内的文件文件夹，我只放了这段代码:

import type { NextRequest } from "next/server";
import { NextResponse } from "next/server";

export function middleware(request: NextRequest) {
  console.log("request", JSON.stringify(request));
  return NextResponse.next();
}

控制台日志被多次点击。我想应该是一次吧？对于这个新的 Next.js 安装，我需要做任何配置吗？

注意:我将在 middleware 中执行一些 cookie 逻辑。用于身份验证。截图:

Answer 1

这是正常现象，因为中间件默认会针对每个请求运行，包括用于获取 JavaScritp、CSS 和图像文件等资源的请求。正如您可以在 doc 上看到的那样:

Middleware will be invoked for every route in your project. The following is the execution order:

1. headers from next.config.js
2. redirects from next.config.js
3. Middleware (rewrites, redirects, etc.)
4. beforeFiles (rewrites) from next.config.js
5. Filesystem routes (public/, _next/static/, pages, etc.)
6. afterFiles (rewrites) from next.config.js
7. Dynamic Routes (/blog/[slug])
8. fallback (rewrites) from next.config.js

如果您添加console.log(request.nextUrl.pathname)，您将看到它运行的不同路径。要让它仅对某些路径执行，您需要使用 conditional statements或matcher配置，如下所示:

// middleware.ts

import type { NextRequest } from "next/server";
import { NextResponse } from "next/server";

export function middleware(request: NextRequest) {
  console.log("Request for : ", request.nextUrl.pathname);
  return NextResponse.next();
}

export const config = {
  // The above middleware would only run for the "/" path
  matcher: '/',
}

另一个经常使用的匹配模式是这个:

// middleware.ts

import type { NextRequest } from "next/server";
import { NextResponse } from "next/server";

export function middleware(request: NextRequest) {
  console.log("Request for : ", request.nextUrl.pathname);
  return NextResponse.next();
}

export const config = {
  matcher: [
    /*
     * Match all request paths except for the ones starting with:
     * - api (API routes)
     * - _next/static (static files)
     * - _next/image (image optimization files)
     * - favicon.ico (favicon file)
     */
    '/((?!api|_next/static|_next/image|favicon.ico).*)',
  ],
}