ilmoralito/mime.html

## mime.html
<html>
<head>
    <script type="text/javascript" src="/jquery.min.js"></script>
    <title>Mime type checker</title>
    <script>
        $(function () {
            var result = $('div#result');
            if (window.FileReader && window.Blob) {
                $('span#submit').click(function () {
                    var files = $('input#file').get(0).files;
                    if (files.length > 0) {
                        var file = files[0];
                        console.log('Loaded file: ' + file.name);
                        console.log('Blob mime: ' + file.type);

                        var fileReader = new FileReader();
                        fileReader.onloadend = function (e) {
                            var arr = (new Uint8Array(e.target.result)).subarray(0, 4);
                            var header = '';
                            for (var i = 0; i < arr.length; i++) {
                                header += arr[i].toString(16);
                            }
                            console.log('File header: ' + header);

                            // Check the file signature against known types
                            var type = 'unknown';
                            switch (header) {
                                case '89504e47':
                                    type = 'image/png';
                                    break;
                                case '47494638':
                                    type = 'image/gif';
                                    break;
                                case 'ffd8ffe0':
                                case 'ffd8ffe1':
                                case 'ffd8ffe2':
                                    type = 'image/jpeg';
                                    break;
                                case '25504446':
                                    type = 'application/pdf';
                                    break;
                            }

                            if (file.type !== type) {
                                result.html('<span style="color: red; ">Mime type detected: ' + type + '. Does not match file extension.</span>');
                            } else {
                                result.html('<span style="color: green; ">Mime type detected: ' + type + '. Matches file extension.</span>');
                            }
                        };
                        fileReader.readAsArrayBuffer(file);
                    }
                });
            } else {
                result.html('<span style="color: red; ">Your browser is not supported. Sorry.</span>');
                console.error('FileReader or Blob is not supported by browser.');
            }
        });
    </script>
    <style>
        .submit {
            border: 1px grey solid;
            padding: 3px;
            position: relative;
            top: 10px;
            cursor: pointer;
        }
    </style>
</head>
<body>
Check mime type of your file in one click<br>
<input type="file" id="file"><br>
<div id="result"></div>
<span class="submit" id="submit">Check</span>
</body>
</html>
	<html>
	<head>
	<script type="text/javascript" src="/jquery.min.js"></script>
	<title>Mime type checker</title>
	<script>
	$(function () {
	var result = $('div#result');
	if (window.FileReader && window.Blob) {
	$('span#submit').click(function () {
	var files = $('input#file').get(0).files;
	if (files.length > 0) {
	var file = files[0];
	console.log('Loaded file: ' + file.name);
	console.log('Blob mime: ' + file.type);

	var fileReader = new FileReader();
	fileReader.onloadend = function (e) {
	var arr = (new Uint8Array(e.target.result)).subarray(0, 4);
	var header = '';
	for (var i = 0; i < arr.length; i++) {
	header += arr[i].toString(16);
	}
	console.log('File header: ' + header);

	// Check the file signature against known types
	var type = 'unknown';
	switch (header) {
	case '89504e47':
	type = 'image/png';
	break;
	case '47494638':
	type = 'image/gif';
	break;
	case 'ffd8ffe0':
	case 'ffd8ffe1':
	case 'ffd8ffe2':
	type = 'image/jpeg';
	break;
	case '25504446':
	type = 'application/pdf';
	break;
	}

	if (file.type !== type) {
	result.html('<span style="color: red; ">Mime type detected: ' + type + '. Does not match file extension.</span>');
	} else {
	result.html('<span style="color: green; ">Mime type detected: ' + type + '. Matches file extension.</span>');
	}
	};
	fileReader.readAsArrayBuffer(file);
	}
	});
	} else {
	result.html('<span style="color: red; ">Your browser is not supported. Sorry.</span>');
	console.error('FileReader or Blob is not supported by browser.');
	}
	});
	</script>
	<style>
	.submit {
	border: 1px grey solid;
	padding: 3px;
	position: relative;
	top: 10px;
	cursor: pointer;
	}
	</style>
	</head>
	<body>
	Check mime type of your file in one click<br>
	<input type="file" id="file"><br>
	<div id="result"></div>
	<span class="submit" id="submit">Check</span>
	</body>
	</html>