Callback a function after a process

I use the bittorent-tracker package for get numbers of seeders and leechers for a given torrent but there is no way to know if the torrent scraping procedure is terminated client.on('scrape_terminated') for exemple ... Is there a way to detects the scraping is terminated ?

var Tracker = require('bittorrent-tracker')
var magnet = require('magnet-uri')
var magnetURI = "magnet:?xt=urn:btih:7a0e02e22744ddb807480f580cc328925d5810d4&dn=Terminator+2%3A+Judgment+Day+DC+%281991%29+1080p+BrRip+x264+-+YIFY&tr=udp%3A%2F%2Ftracker.leechers-paradise.org%3A6969&tr=udp%3A%2F%2Fzer0day.ch%3A1337&tr=udp%3A%2F%2Fopen.demonii.com%3A1337&tr=udp%3A%2F%2Ftracker.coppersurfer.tk%3A6969&tr=udp%3A%2F%2Fexodus.desync.com%3A6969"

var parsedTorrent = magnet(magnetURI)

var opts = {
infoHash: parsedTorrent.infoHash,
announce: parsedTorrent.announce,
peerId: new Buffer('01234567890123456789'), // hex string or Buffer
port: 6881 // torrent client port
}

var client = new Tracker(opts)

client.scrape();

client.on('scrape', function (data) {
 console.log('number of seeders in the swarm: ' + data.complete)
 console.log('number of leechers in the swarm: ' + data.incomplete)
});

client.on('error',function(data) {
 console.log('erreur');
})

via LeSpotted44