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 '/'，改为你的博客地址
  const DOMAIN = 'xxx.com';
  // 博客插入的js地址文件名，可自定义
  const JS_FILE = 'ga.js'
  // 响应上报的接口路径，可自定义，规避广告屏蔽插件拦截
  const COLLECT_PATH = 'collect_path';
  // 原 gtag 地址，将G-XXX改为你的id
  const JS_URL = 'https://www.googletagmanager.com/gtag/js?id=G-XXX'
  
  // 下面不需要改
  const G_DOMAIN = 'google-analytics.com';
  const G_COLLECT_PATH = 'g\/collect';
  
  async function handleRequest(event) {
    const url = event.request.url;
    if (url.match(`${DOMAIN}/${JS_FILE}`)) {
      const requestJs = await (await fetch(JS_URL)).text();
      const jsText = requestJs.replaceAll('\"www\"', '\"\"').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}`, `www.${G_DOMAIN}/${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);
  }

<!-- Google tag (gtag.js) -->
<script async src="https://xxx.com/ga.js"></script> // 对应worker里的DOMAIN 和 JS_FILE，需要保持一致
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());

  gtag('config', 'G-XXX'); // 将G-XXX改为你的id
</script>

Minimal Google Analytics Snippet
A simple snippet for tracking page views on your website without having to add external libraries. Also works for single page applications made with the likes of react and vue.js.

Before
Google Tag Manager + Analytics = 73kB

After
Snippet = 1.5kB

<script>
enScroll=!1,enFdl=!1,extCurrent=void 0,filename=void 0,targetText=void 0,splitOrigin=void 0;const lStor=localStorage,sStor=sessionStorage,doc=document,docEl=document.documentElement,docBody=document.body,docLoc=document.location,w=window,s=screen,nav=navigator||{},extensions=["pdf","xls","xlsx","doc","docx","txt","rtf","csv","exe","key","pps","ppt","pptx","7z","pkg","rar","gz","zip","avi","mov","mp4","mpe","mpeg","wmv","mid","midi","mp3","wav","wma"];function a(e,t,n,o){const j="G-G9ZDJQN9E2",r=()=>Math.floor(Math.random()*1e9)+1,c=()=>Math.floor(Date.now()/1e3),F=()=>(sStor._p||(sStor._p=r()),sStor._p),E=()=>r()+"."+c(),_=()=>(lStor.cid_v4||(lStor.cid_v4=E()),lStor.cid_v4),m=lStor.getItem("cid_v4"),v=()=>m?void 0:enScroll==!0?void 0:"1",p=()=>(sStor.sid||(sStor.sid=c()),sStor.sid),O=()=>{if(!sStor._ss)return sStor._ss="1",sStor._ss;if(sStor.getItem("_ss")=="1")return void 0},a="1",g=()=>{if(sStor.sct)if(enScroll==!0)return sStor.sct;else x=+sStor.getItem("sct")+ +a,sStor.sct=x;else sStor.sct=a;return sStor.sct},i=docLoc.search,b=new URLSearchParams(i),h=["q","s","search","query","keyword"],y=h.some(e=>i.includes("&"+e+"=")||i.includes("?"+e+"=")),u=()=>y==!0?"view_search_results":enScroll==!0?"scroll":enFdl==!0?"file_download":"page_view",f=()=>enScroll==!0?"90":void 0,C=()=>{if(u()=="view_search_results"){for(let e of b)if(h.includes(e[0]))return e[1]}else return void 0},d=encodeURIComponent,k=e=>{let t=[];for(let n in e)e.hasOwnProperty(n)&&e[n]!==void 0&&t.push(d(n)+"="+d(e[n]));return t.join("&")},A=!1,S="https://xxx.com/collect_path",M=k({v:"2",tid:j,_p:F(),sr:(s.width*w.devicePixelRatio+"x"+s.height*w.devicePixelRatio).toString(),ul:(nav.language||void 0).toLowerCase(),cid:_(),_fv:v(),_s:"1",dl:docLoc.origin+docLoc.pathname+i,dt:doc.title||void 0,dr:doc.referrer||void 0,sid:p(),sct:g(),seg:"1",en:u(),"epn.percent_scrolled":f(),"ep.search_term":C(),"ep.file_extension":e||void 0,"ep.file_name":t||void 0,"ep.link_text":n||void 0,"ep.link_url":o||void 0,_ss:O(),_dbg:A?1:void 0}),l=S+"?"+M;if(nav.sendBeacon)nav.sendBeacon(l);else{let e=new XMLHttpRequest;e.open("POST",l,!0)}}a();function sPr(){return(docEl.scrollTop||docBody.scrollTop)/((docEl.scrollHeight||docBody.scrollHeight)-docEl.clientHeight)*100}doc.addEventListener("scroll",sEv,{passive:!0});function sEv(){const e=sPr();if(e<90)return;enScroll=!0,a(),doc.removeEventListener("scroll",sEv,{passive:!0}),enScroll=!1}document.addEventListener("DOMContentLoaded",function(){let e=document.getElementsByTagName("a");for(let t=0;t<e.length;t++)if(e[t].getAttribute("href")!=null){const n=e[t].getAttribute("href"),s=n.substring(n.lastIndexOf("/")+1),o=s.split(".").pop();(e[t].hasAttribute("download")||extensions.includes(o))&&e[t].addEventListener("click",fDl,{passive:!0})}});function fDl(e){enFdl=!0;const t=e.currentTarget.getAttribute("href"),n=t.substring(t.lastIndexOf("/")+1),s=n.split(".").pop(),o=n.replace("."+s,""),i=e.currentTarget.text,r=t.replace(docLoc.origin,"");a(s,o,i,r),enFdl=!1}
</script>