Monkey patch XMLHTTPRequest.onreadystatechange

Question

How would go about monkey patching the XMLHTTPRequest\'s onreadystatechange function. I\'m trying to add a function that would be called when every

Answer 1

Assuming you can ignore IE...

//Totally untested code, typed at the SO ... but the concept *should* work, let me know if it doesn't.
var OldXMLRequest = XMLHttpRequest;

// Create a new instance
function XMLHttpRequest() {
  var ajax = new OldXMLRequest();

  // save old function
  var f = ajax.onreadystatechange;
  ajax.onreadystatechange = function() {
    console.log("Whatever!");
    f(); // Call the old function
  }
  return ajax;
}
</code></pre>
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