Today i’have created a simple class to log in the backend the javascript error, so i can have a real time monitoring of how error appear to the users.

We can use a window.onerror and the addEventListener rewrite.

Window.onerror has been available in most browser, but the argument that are passed on each browser are different:

IE 11
IE 10
IE 9, 8
Safari 10 and up
Safari 9
Android Browser 4.4

This is my class with a _wrap function, and a SendError that trasmit the data on the backend

class ErrorHandler {

	constructor() {
		let $this = this;

		window.onerror = function (message, file, line, col, error) {
			let data = message+" from "+error.stack;

	_prototypeInit() {
		let $this = this;
		var addEventListener = window.EventTarget.prototype.addEventListener;
		window.EventTarget.prototype.addEventListener = function (event, callback, bubble) {, event, $this._wrap(callback), bubble);
		var removeEventListener = window.EventTarget.prototype.removeEventListener;
		window.EventTarget.prototype.removeEventListener = function (event, callback, bubble) {, event, callback._wrapped || callback, bubble);

	_wrap(func) {
		let $this = this;
		if (!func._wrapped) {
			func._wrapped = function () {
				try {
					func.apply(this, arguments);
				} catch (e) {
					let data = e.message+" from "+e.stack;
					throw e;
		return func._wrapped;

	SendError(message) {
		let $this = this;
		fetch('/ErrorHandler/WriteLog', {
			method: 'POST',
			body: JSON.stringify({ message: message }),
			headers: {
				'Content-Type': 'application/json'
		}).then(res => res.json()).catch(error => console.error('Error:', error));

In the message we put the stacktrace.
To use it at the init of your application:
let handlerError = new HandlerError();

Write to me if you have some suggestion to improve it.


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