Worker to grab the meta tags of a site

worker.js

// Single-line install of CFW-EU (https://www.npmjs.com/package/cfw-easy-utils)
var cfweu = {};function t(e){var t="",s="0123456789abcdef";return new Uint8Array(e).forEach((e=>{t+=s[e>>4]+s[15&e]})),t}const s={uuidv4:()=>([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g,(e=>(e^crypto.getRandomValues(new Uint8Array(1))[0]&15>>e/4).toString(16))),async hashPassword(e,s){var r=(s=s||{}).salt||crypto.getRandomValues(new Uint8Array(8)),n=s.iterations||45e3;"string"==typeof r&&(r=function(e){(e=e.replace(/^0x/,"")).length%2!=0&&console.log("WARNING: expecting an even number of characters in the hexString");var t=e.match(/[G-Z\s]/i);t&&console.log("WARNING: found non-hex characters",t);var s=e.match(/[\dA-F]{2}/gi).map((function(e){return parseInt(e,16)}));return new Uint8Array(s).buffer}(r));const a=new TextEncoder("utf-8").encode(e),i=await crypto.subtle.importKey("raw",a,{name:"PBKDF2"},!1,["deriveBits","deriveKey"]),o=await crypto.subtle.deriveKey({name:"PBKDF2",salt:r,iterations:n,hash:"SHA-256"},i,{name:"AES-CBC",length:256},!0,["encrypt","decrypt"]);return`$PBKDF2;h=${t(await crypto.subtle.exportKey("raw",o))};s=${t(r)};i=${n};`},async validatePassword(e,t){for(var s={salt:t.split(";s=")[1].split(";")[0],iterations:t.split(";i=")[1].split(";")[0]},r=await this.hashPassword(e,s),n=!0,a=0;a<r.length;a++)r.charAt(a)!=t.charAt(a)&&(n=!1);return n}};const r={version:"1.0.0",config:{secretKey:"password",debugHeaders:!1},accessControl:{allowOrigin:"*",allowMethods:"GET, POST, PUT",allowHeaders:"Content-Type"},request:null,_corsHeaders(){var e=this.accessControl.allowOrigin;return this.request&&(e=new URL(this.request.url).origin),{"Access-Control-Allow-Origin":e,"Access-Control-Allow-Methods":this.accessControl.allowMethods,"Access-Control-Max-Age":"1728000"}},injectCors(e,t){this._corsHeaders()},_genericResponse(e,t,s){if(void 0===s)s={};var r=s.headers||{},n=s.status||200,a=s.statusText||"OK",i=s.autoCors;void 0===s.autoCors&&(i=!0);var o=s.cookies||null,c=s.stopwatch||null,h={"Content-Type":e,...r};i&&(h={...h,...this._corsHeaders()});var l=new Response(t,{status:n,statusText:a,headers:h});o&&o.values().forEach((e=>{l.headers.append("Set-Cookie",e)}));return c&&l.headers.set("Server-Timing",c.getHeader()),this.config.debugHeaders&&l.headers.set("x-cfw-eu-version",this.version),new Promise((e=>e(l)))},cors(e){return e&&(this.request=e),new Response(null,{headers:this._corsHeaders()})},json(e,t){var s=e;return"string"!=typeof s&&(s=JSON.stringify(e)),this._genericResponse("application/json",s,t)},html(e,t){return this._genericResponse("text/html",e,t)},text(e,t){return this._genericResponse("plain/text",e,t)},fromResponse(e,t){var s={...this.headersToObject(e.headers),...t.headers||{}};"headers"in t&&delete t.headers;var r=JSON.parse(JSON.stringify(s["content-type"]));return"content-type"in s&&delete s["content-type"],this._genericResponse(r,e.body,{headers:s,...t})},async static(e,t){var s=t.baseUrl;if(!s)throw"You need to specify a baseUrl for response.static to work.";let r=new URL(e.url);var n=await fetch(`${s}${r.pathname.replace(t.routePrefix||"<>","")}`,{cf:{cacheTtl:t.ttl||600}});return this.fromResponse(n,t)},websocket:async e=>new Response(null,{status:101,webSocket:e.client}),setHeader(e,t,s){var r=new Response(e.body,e),n=s;return"function"==typeof s.values?(n=s.values()).forEach((e=>{r.headers.append(t,e)})):r.headers.append(t,n),r},headersToObject:e=>Object.fromEntries(e.entries())};cfweu.Stopwatch=class{constructor(){this.start=new Date,this.checkpoints=[{name:"Start",dur:0,desc:"Started recording"}],this.lastCheckpointTime=new Date}mark(e,t){console.log("Last checkpoint: ",this.lastCheckpointTime),console.log(new Date),console.log("Difference: ",new Date-this.lastCheckpointTime),this.checkpoints.push({name:e,time:new Date,dur:new Date-this.lastCheckpointTime,...t}),this.lastCheckpointTime=new Date}getTotalTime(){return new Date-this.start}join(e){var t=this.checkpoints+e.checkpoints;this.checkpoints=t.sort(((e,t)=>t.time-e.time))}getHeader(){var e=[];return this.checkpoints.forEach((t=>{var s=[t.name];Object.keys(t).forEach((e=>{"name"!=e&&"time"!=e&&s.push(`${e}=${t[e]}`)})),e.push(s.join(";"))})),e.join(",")}},cfweu.Websocket=class{constructor(t,s){this.url=t,this.options=s,this.emitter=e.createNanoEvents(),this.sendQueue=[],this.url.includes("wss:")&&(this.url=this.url.replace("wss:","https:")),this.url.includes("ws:")&&(this.url=this.url.replace("ws:","http:")),this.connect()}log(e){this.options.logger&&this.options.logger.send(e)}async connect(){var e=await fetch(this.url,{headers:{upgrade:"websocket"}});this.socket=e.webSocket,this.socket.accept(),this.socket.addEventListener("message",(e=>{this.emitter.emit("rawmessage",e);var t=e.data;try{"string"==typeof(t=JSON.parse(t))&&(t=e.data)}catch(e){}this.emitter.emit("message",t)})),this.socket.addEventListener("close",(()=>{this.emitter.emit("close")})),this.sendQueue.forEach((e=>{this.socket.send(e)})),this.sendQueue=[]}on(e,t){return this.emitter.on(e,t)}addEventListener(e,t){return"message"==e&&(e="rawmessage"),this.emitter.on(e,t)}send(e,t){var s=e;e.constructor!=Object&&e.constructor!=Array||(s=JSON.stringify(s)),this.socket?this.socket.send(s):this.sendQueue.push(s)}},cfweu.WebsocketResponse=class{constructor(){let t=new WebSocketPair;this.socket=t[1],this.client=t[0],this.socket.accept(),this.emitter=e.createNanoEvents(),this.session={history:[],startTime:new Date,lastMessageTime:null},this.socket.addEventListener("message",(e=>{var t=e.data;try{"string"==typeof(t=JSON.stringify(t))&&(t=e.data)}catch(e){}this.session.lastMessageTime=new Date,this.emitter.emit("message",t)})),this.socket.addEventListener("close",(()=>this.emitter.emit("close")))}on(e,t){return this.emitter.on(e,t)}send(e,t){var s=e;e.constructor!=Object&&e.constructor!=Array||(s=JSON.stringify(s)),this.socket.send(s)}},cfweu.response=r,cfweu.secrets=s;
var { response } = cfweu

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

/**
 * Fetch and log a given request object
 * @param {Request} request
 */
async function handleRequest(request) {
  var url = new URL(request.url).searchParams.get('url')

  var resp = await fetch(
    url + '?_escaped_fragment_=1',
    {
      headers: {
        // Trick the website into thinking we are a search engine.
        // This may trigger a pre-render or SSR situation which will return our meta tags.
        'user-agent': ' Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)'
      }
    }
  )

  var metadata = {}

  class Scraper {
    constructor() {
      this.values = {}
    }

    element(element) {
      var property = element.getAttribute('property')

      this.values[property] = element.getAttribute('content')
    }
  }

  const scraper = new Scraper()

  await new HTMLRewriter().on('meta', scraper).transform(resp).arrayBuffer()

  return response.json({url, metadata: scraper.values})
}