index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>NML to Tracklist</title>
</head>

<body>
    <div>
        <input type="file" id="input" onchange="readFile(this.files)">

        <button id="copy">Copy to clipboard</button>
    </div>

    <div>
        <pre id="result"></pre>
    </div>

    <script>
        function copyTrackListToClipboard() {
            var textArea = document.createElement('textarea');
            var textToCopy = document.querySelector('#result');

            textArea.value = textToCopy.innerText;
            document.body.appendChild(textArea);
            textArea.select()
            
            document.execCommand('copy');

            document.body.removeChild(textArea);
        }

        document.querySelector('#copy').addEventListener('click', copyTrackListToClipboard);

        function readFile(files) {
            var fileReader = new FileReader();
            fileReader.onload = function (event) {
                parseNML(fileReader.result);
            };
            fileReader.readAsText(files[0]);
        }

        function parseNML(string) {
            var parser = new DOMParser();
            var tracklist = parser.parseFromString(string, 'application/xml');

            var nsResolver = tracklist.createNSResolver(tracklist.documentElement);
            var collectionEntries = tracklist.evaluate('/NML/COLLECTION/ENTRY', tracklist, nsResolver, XPathResult
                .ANY_TYPE, null);
            var playlistEntries = tracklist.evaluate(
                '/NML/PLAYLISTS//PLAYLIST/ENTRY/PRIMARYKEY', tracklist, nsResolver,
                XPathResult.ANY_TYPE, null);

            var tracks = {};
            while (entry = collectionEntries.iterateNext()) {
                tracks[entry.children[0].getAttribute('FILE')] = {
                    'artist': entry.getAttribute('ARTIST'),
                    'title': entry.getAttribute('TITLE'),
                };
            }

            var playlist = [];
            while (entry = playlistEntries.iterateNext()) {
                playlist.push(entry.getAttribute('KEY').split(':').pop());
            }

            var orderedTracklist = [];
            playlist.forEach((filename) => {
                orderedTracklist.push(tracks[filename]);
            });

            var formatted = orderedTracklist.map((track, index) => {
                index += 1;
                index = index < 10 ? '0' + index : index;
                return `${index} - ${track.artist} - ${track.title}`;
            });

            var formattedText = formatted.reduce((previousValue, currentValue, index) => {
                return `${previousValue}\n${currentValue}`;
            });

            document.getElementById('result').innerText = formattedText;
        }
    </script>
</body>

</html>