Google Analytics 4 Proxy with Cloudflare Workers

gaWorker.js

// 2023.4.23 更新，修复 gtag.js 加了个回车导致失效的问题
// 2023.3.2 更新，修复上报到 region*.google-analytics.com 未被代理的问题

addEventListener('fetch', (event) => {
  // 这里可以加 filter
  return event.respondWith(handleRequest(event));
});

// worker 应用的路由地址，末尾不加 '/'
const DOMAIN = 'https://example.workers.dev/routerpath'; 
// 响应上报的接口路径，可自定义
const COLLECT_PATH = 'any-collect-dest-path';
// 原 gtag 地址
const JS_URL = 'https://www.googletagmanager.com/gtag/js?id=G-**********'

// 下面不需要改
const G_DOMAIN = /https\:\/\/[a-z"+\s]*\.google-analytics\.com/g;
const G_COLLECT_PATH = 'g\/collect';

async function handleRequest(event) {
  const url = event.request.url;
  if (url.match(`${DOMAIN}/a.js`)) {
    const requestJs = await (await fetch(JS_URL)).text();
    const jsText = requestJs.replaceAll(G_DOMAIN, DOMAIN).replaceAll(G_COLLECT_PATH, COLLECT_PATH);
    return new Response(jsText, {
      status: 200,
      statusText: 'OK',
      headers: {
        'Content-Type': 'application/javascript',
      },
    });
  } else if (url.match(`${DOMAIN}/${COLLECT_PATH}`)) {
      const newReq = await readRequest(event.request);
      event.waitUntil(fetch(newReq));
  }
  return new Response(null, {
    status: 204,
    statusText: 'No Content',
  });
}

async function readRequest(request) {
  const { url, headers } = request;
  const body = await request.text();
  const ga_url = url.replace(`${DOMAIN}/${COLLECT_PATH}`, `https://www.google-analytics.com/${G_COLLECT_PATH}`);
  const nq = {
    method: 'POST',
    headers: {
      Host: 'www.google-analytics.com',
      Origin: headers.get('origin'),
      'Cache-Control': 'max-age=0',
      'User-Agent': headers.get('user-agent'),
      Accept: headers.get('accept'),
      'Accept-Language': headers.get('accept-language'),
      'Content-Type': headers.get('content-type') || 'text/plain',
      Referer: headers.get('referer'),
    },
    body: body,
  };
  return new Request(ga_url, nq);
}