Cloudflare Worker script for customizing web search

custom-web-search.js

// Cloudflare Worker script to automatically redirect search queries based on trigger words

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

// status code for redirect response; need something that won't cache
var statuscode = 303

    
// defining base URLs for search engines
var googleurl = "https://www.google.com/search?q="
var ddgurl = "https://www.duckduckgo.com/html/?q="
var duckyurl = "https://www.duckduckgo.com/html/?q=!+"


// if any of these words are in the query, show full search results
var filterwords = ["why","who","how","what","where","django","python","jquery","javascript","error", "etymology"]

// we only want to match these words, not substrings (e.g., don't match something like "howard")
var regex_string = "\\b(" + filterwords.join("|") + ")\\b"


async function handleRequest(request) {

  // get the query from the page URL
  const { searchParams } = new URL(request.url);
  var query = searchParams.get('q');

  // if the query contains any bangs, pass to DDG
  if (new RegExp(/!([a-zA-Z]+)\b/).test(query)) {

  var url = ddgurl + encodeURIComponent(query).replace(/%20/g,"+");

  // if the query contains any filter words, pass it to Google
  } else if (new RegExp(regex_string).test(query)) {

  var url = googleurl + encodeURIComponent(query).replace(/%20/g,"+");;
    
  // otherwise, pass the query to "I'm Feeling Ducky"
  } else {
  
  var url = duckyurl + encodeURIComponent(query).replace(/%20/g,"+");
  }
  
  // redirect to the correct URL
  return Response.redirect(url, statuscode)
}