It doesn’t work anymore. It requires token. But this still works:
$.ajax({url: 'https://api.twitch.tv/kraken/users/'+payload.user_id,
method:'GET',
headers:{'client-id':auth.clientId,
Accept: 'application/vnd.twitchtv.v5+json'} } ).
done(function(data){
console.log(data);
});