app.js

const searchParams = new URLSearchParams(window.location.search);
const cid = searchParams.get('cid') || 'Qmaisz6NMhDB51cCvNWa1GMS7LU1pAxdF4Ld6Ft9kZEP2a'
const corsApi = searchParams.get('cors') || ''
const hashToTest = cid
const hashString = 'Hello from IPFS Gateway Checker'

const $results = document.querySelector('#results')

function returnHtmlLink (gateway) {
  let gatewayTitle = gateway.split(hashToTest)[0]
  return '<a title="' + gatewayTitle + '" href="' + gateway + '">' + gateway + '</a>'
}

function addNode (gateway, online, status, roundtripInMs) {
  const para = document.createElement('div')
  let node
  if (online) {
    node = document.createElement('strong')
    node.innerHTML = '✅ - Online  - ' + returnHtmlLink(gateway)
    node.innerHTML += ' (' + roundtripInMs + 'ms)'
  } else {
    node = document.createElement('div')
    node.innerText = '❌ - Offline - ' + gateway
  }
  node.setAttribute('title', status)
  para.appendChild(node)
  $results.appendChild(para)
}

function updateStats (total, checked) {
  document.getElementById('stats').innerText = checked + '/' + total + ' gateways checked'
}

function checkGateways (gateways) {
  const total = gateways.length
  let checked = 0
  gateways.forEach((gateway) => {
    const gatewayAndHash = gateway.replace(':hash', hashToTest)
    // opt-out from gateway redirects done by browser extension
    const corsHost = corsApi
    const testUrl = gatewayAndHash + '#x-ipfs-companion-no-redirect'
    const start = performance.now()
    fetch(corsHost+testUrl)
      .then(res => {
        if(res.status === 200){
          return true;
        }else{
          return Promise.reject(false);
        }
      })
      .then(() => {
        // console.log('text',text);
        // const matched = text.trim() === hashString.trim()
        // const status = matched ? 'All good' : 'Output did not match expected output'
        const matched = true;
        const status = 'All good'
        const ms = performance.now() - start
        addNode(gatewayAndHash, matched, status, ms);
        checked++
        updateStats(total, checked)
      }).catch((err) => {
        window.err = err
        addNode(gatewayAndHash, false, err)
        checked++
        updateStats(total, checked)
      })
  })
}

fetch('./gateways.json')
  .then(res => res.json())
  .then(gateways => checkGateways(gateways))