<!DOCTYPE html>
<html>
<head>
</head>
<body>
<h1>Test page</h1>
<p>Hello!</p>

<script type="text/javascript">
	var dummyscript = document.createElement('script');

	// Register error function where the file does not exist.
	dummyscript.onerror = function() {
		if (dummyscript.onerror)
			alert("The file does not exist.");
	}

	// Append some random data to the file name so that the browser cache doesn't serve an old result.
	dummyscript.src = "file:///C:/Temp/testfile?" + new Date().getTime() + Math.floor(Math.random() * 1000000);

	// Load dummy script
	document.body.appendChild(dummyscript);
</script>

</body>
</html>

But, the web browser displays "Not allowed to load local resource: file:///C:/Temp/testfile?~~~~~~".