hijack-xmlhttprequest.js

// <script>
class myXMLHttpRequest extends XMLHttpRequest {
  constructor() {
    super();
    this._open = this.open;
    this.open = (method, target) => {
      // TODO replace file: with http/https: here
      console.warn(target);
      var base = "https://gist.github.com/snshn/a3f09016986abb04da16b80382f6adc5";
      return this._open(method, new URL(target, base));
    }
  }
}
XMLHttpRequest = myXMLHttpRequest;
// </script>


//////////////////////
// Proof of concept //
//////////////////////
var oReq = new XMLHttpRequest();

oReq.onload = function(e) {
  var ab = oReq.response;
  const decoder = new TextDecoder();
  const str = decoder.decode(ab)
  console.log(str);
}
oReq.open("GET", '/');
oReq.responseType = "arraybuffer";
oReq.send();