test.html

<!doctype html>
<html>
<head>
    <title>WebTorrent – Simple File Sending Example</title>
    <style>
        body {
            font-family: sans-serif;
        }
    </style>
</head>
<body>
<h1>Streaming File Transfer over <a href="http://webtorrent.io">WebTorrent</a></h1>

<p>Download files using the WebTorrent protocol (BitTorrent over WebRTC).</p>

<h2>Log</h2>
<div class="log"></div>

<h2>Start downloading</h2>

<form>
    <label for="torrentId">Download from a magnet link or info hash</label>
    <input name="torrentId", placeholder="magnet:">
    <button type="submit">Download</button>
</form>

<br>
<p><small>Code is available on <a href="https://github.com/feross/instant.io">GitHub</a> under MIT License. Run <code>localStorage.debug = '*'</code> in the console and refresh to enable verbose logs.</small></p>

<!-- Include the latest version of WebTorrent -->
<script src="https://cdn.jsdelivr.net/webtorrent/latest/webtorrent.min.js"></script>

<script>
    var client = new WebTorrent()
    // Print warnings and errors to the console
    client.on('warning', function (err) {
        console.log('WARNING: ' + err.message)
    })
    client.on('error', function (err) {
        console.error('ERROR: ' + err.message)
    })
    document.querySelector('form').addEventListener('submit', onSubmit)
    function onSubmit (e) {
        e.preventDefault() // Prevent page refresh
        var torrentId = document.querySelector('form input[name=torrentId]').value
        client.add(torrentId, onTorrent)
    }
    function onTorrent (torrent) {
        alert('torrent')
        log(
                'Torrent info hash: ' + torrent.infoHash + ' ' +
                '<a href="' + torrent.magnetURI + '" target="_blank">[Magnet URI]</a> ' +
                '<a href="' + torrent.torrentFileURL + '" target="_blank" download="' + /*torrentFileName + */'">[Download .torrent]</a>'
        )
        torrent.files.forEach(function (file) {
            file.appendTo('.log')
            var meshID=file.name.split('.')[0]
            console.log('i know',meshID)
        })
    }
    function log (str) {
        var p = document.createElement('p')
        p.innerHTML = str
        document.querySelector('.log').appendChild(p)
    }
</script>
</body>
</html>