cloudflare-worker-strip-query-param.js

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


async function handleRequest(request) {
  
  let url = new URL(request.url)
  
  //strip out utm tags
  var deleteKeys = []

  for(var key of url.searchParams.keys()) { 
    if(key.toLowerCase().startsWith('utm')){
      deleteKeys.push(key)
    }
  }
  for(var key of deleteKeys){
    url.searchParams.delete(key);
  }
  
  let modifiedRequest = new Request(url, request)

  return fetch(modifiedRequest)
}