JavaScript window.onerror

onerror.js

window.onerror = function (msg, url, line) {
  var idx = url.lastIndexOf("/");
  if (idx > -1) {
    url = url.substring(idx + 1);
  }
  //Build the message string we'll display to the user
  var errStr = "ERROR in " + url + " (line #" + line + "): " + msg;
  //Write the error to the console
  console.error(errStr);
  //Tell the user what happened
  alert(errStr);
  return false;
};