Chrome extension: Block page items before access

Question

I am trying to do block items on a webpage but I want to do that, before they are loaded. So, e.g., I could use

chrome.webRequest.onBeforeRequest.addListener(

Answer 1

I believe you can use arraybuffers to read the content in real-time.

Here's an example of loading a file / page into a buffer;

var oReq = new XMLHttpRequest();
oReq.open("GET", "/myfile.png", true);
oReq.responseType = "arraybuffer";

oReq.onload = function (oEvent) {
  var arrayBuffer = oReq.response; // Note: not oReq.responseText
  if (arrayBuffer) {
    var byteArray = new Uint8Array(arrayBuffer);
    for (var i = 0; i < byteArray.byteLength; i++) {
      // do something with each byte in the array
    }
  }
};

oReq.send(null);

This is a piece of code found on the XMLHttpRequest documentation page. Link.