getify/dispatch-error-event.js

## dispatch-error-event.js
var dispatchErrorEvent = (function IIFE(){

  var createErrorEvent;

  try {
    try {
      new ErrorEvent("error",{});
      createErrorEvent = function createErrorEvent(err) {
        return new ErrorEvent("error",{
          error: err,
          message: err.message || "general error event"
        });
      };
      return dispatchError;
    }
    catch(err){}

    var x = document.createEvent("Event");
    x.initEvent("error",false,false);
    createErrorEvent = function createErrorEvent(err) {
      var e = document.createEvent("Event");
      e.initEvent("error",false,false);
      e.message = err.message || "general error event";
      return e;
    };
    return dispatchError;
  }
  catch(err) {}
  return Function.prototype;  // no-op

  function dispatchError(err) {
    window.dispatchEvent(createErrorEvent(err));
  }
})();

## test-error-1.js
function logMsgs() {
	var args = [].slice.call(arguments);
	var elem = document.getElementById("messages");
	elem.innerHTML += "<p>" + args.join(" ; ") + "</p>";
}

window.onerror = function(err){
	logMsgs("onerror",err.message || err);
	return true;
};

window.addEventListener("error",function(evt){
	logMsgs("addEL-1",evt.type,evt.message);
});

window.addEventListener("error",function(evt){
	logMsgs("addEL-2",evt.type,evt.message);
});

## test-error-2.js
function foo() {
	throw new Error("...from foo");
}

function bar() {
	doesntexist1();
}

document.getElementById("clickme").addEventListener("click",bar,false);

setTimeout(function(){
	throw new Error("...from settimeout");
},1000);

dispatchErrorEvent(new Error("...from dispatched event"));

## test-error-3.js
foo();

// note: shouldn't get here
doesntexist2();

## test.html
<!DOCTYPE html>
<html>
<meta charset="utf-8">
<title>Creating, dispatching, and catching error events</title>
<body>
<h1>Creating, dispatching, and catching error events</h1>
<button id="clickme">click me</button>
<div id="messages"></div>
<script src="dispatch-error-event.js"></script>
<script src="test-error-1.js"></script>
<script src="test-error-2.js"></script>
<script src="test-error-3.js"></script>
</body>
</html>
	var dispatchErrorEvent = (function IIFE(){

	var createErrorEvent;

	try {
	try {
	new ErrorEvent("error",{});
	createErrorEvent = function createErrorEvent(err) {
	return new ErrorEvent("error",{
	error: err,
	message: err.message \|\| "general error event"
	});
	};
	return dispatchError;
	}
	catch(err){}

	var x = document.createEvent("Event");
	x.initEvent("error",false,false);
	createErrorEvent = function createErrorEvent(err) {
	var e = document.createEvent("Event");
	e.initEvent("error",false,false);
	e.message = err.message \|\| "general error event";
	return e;
	};
	return dispatchError;
	}
	catch(err) {}
	return Function.prototype; // no-op

	function dispatchError(err) {
	window.dispatchEvent(createErrorEvent(err));
	}
	})();
	function logMsgs() {
	var args = [].slice.call(arguments);
	var elem = document.getElementById("messages");
	elem.innerHTML += "<p>" + args.join(" ; ") + "</p>";
	}

	window.onerror = function(err){
	logMsgs("onerror",err.message \|\| err);
	return true;
	};

	window.addEventListener("error",function(evt){
	logMsgs("addEL-1",evt.type,evt.message);
	});

	window.addEventListener("error",function(evt){
	logMsgs("addEL-2",evt.type,evt.message);
	});
	function foo() {
	throw new Error("...from foo");
	}

	function bar() {
	doesntexist1();
	}

	document.getElementById("clickme").addEventListener("click",bar,false);

	setTimeout(function(){
	throw new Error("...from settimeout");
	},1000);

	dispatchErrorEvent(new Error("...from dispatched event"));
	<!DOCTYPE html>
	<html>
	<meta charset="utf-8">
	<title>Creating, dispatching, and catching error events</title>
	<body>
	<h1>Creating, dispatching, and catching error events</h1>
	<button id="clickme">click me</button>
	<div id="messages"></div>
	<script src="dispatch-error-event.js"></script>
	<script src="test-error-1.js"></script>
	<script src="test-error-2.js"></script>
	<script src="test-error-3.js"></script>
	</body>
	</html>