Vanilla

client.on("friendMessage", (steamid, message) => {
if (message === "test") {
client.getSteamLevels([steamid], function(results) {
if (results[steamid] > 5) {
client.chatMessage(steamid, "u have +5 lvl.");
console.log("done");
}
});
}
});

client.on('webSession', function(sessionID, cookies) { steamcommunity.setCookies(cookies); }); steamcommunity.on("sessionExpired", function(err) { if (err) { client.webLogOn(); } });

Not really an answer, but here's a small code I use on my bot to prevent chat spam.
It will block a person who send same messages every 2 second.
var antispam; var markedSteamID; function spamtimer() { //when called, it will reset antispam = 0; markedSteamID = 0; } setInterval(spamtimer, 2000); //call spamtimer function every 2 sec //.. your code here client.on("friendMessage", function(senderID, message) { //anti spam if (senderID == admin){ //Ignore if chat from admin } else if ((antispam == message) && (markedSteamID == senderID.getSteamID64())) { client.chatMessage(senderID, "I caught you spamming"); //do something, like block that person or something } //.. your code here.. to respond chat antispam = message; //bot will record the message, will reset every 2 sec markedSteamID = senderID.getSteamID64(); //bot will record SteamID of sender, will reset every 2 sec });

Add amount property when adding item
 
https://dev.doctormckay.com/topic/1034-adding-gems-and-gem-sacks-to-trade/?hl=gems
https://github.com/DoctorMcKay/node-steam-tradeoffer-manager/wiki/TradeOffer#addmyitemitem

var id = ""; //either SteamID Object or customURL after /id/ community.getSteamUser(id, function (err, user){ if (err){ console.log(err); //some error } else { console.log(user.summary); } });

Well, I didn't use "pollFailure" on my bot, and I use this solution for my bot
(trying to send offer -> error not logged in -> steam-community "sessionExpired" called -> relogin using client.webLogOn(); -> use if/else and re-send trade offer)

Lol, so that's why I'm unable to add new item. 
 
Now works like a charm, thanks.
 

manager.on('newOffer', function(offer) {    if (offer.partner.getSteamID64() == admin){       //Counter an offer by adding new item var counteroffer = offer.counter();       counteroffer.addMyItem({"appid": 753, "contextid": 6, "assetid": "5222324266"});        counteroffer.send(function(err, status){          if (err){             console.log("Error: "+err);          }          console.log("Status: "+status)       });       //confirmation    } }

using 'item.appid' 
https://github.com/DoctorMcKay/node-steamcommunity/wiki/CEconItem#appid

Using steamcommunity editProfile.https://github.com/DoctorMcKay/node-steamcommunity/wiki/SteamCommunity#editprofilesettings-callback

That means, tradeoffer-manager have invalid cookies, and you need to refresh cookies if that happened.
 
Use steamcommunity "sessionExpired" event to refresh tradeoffer-manager cookies
When you get "Error: Not Logged In", steamcommunity "sessionExpired" event will fired.
community.on("sessionExpired", function(err) { client.webLogOn(); //relogin to Steam or refresh tradeoffer-manager cookies //add your handling code here, for example: if (sendofferError == true){ //do stuff } } Edit: If you want to kill cookies for testing purposes, you can add this in your code:
setTimeout(function(){ //for debugging purposes, kill cookies after 10 second console.log("rip cookies :("); community.setCookies(["steamLogin=1||invalid", "steamLoginSecure=1||invalid"]); manager.setCookies(["steamLogin=1||invalid", "steamLoginSecure=1||invalid"]); }, 10000);

https://github.com/DoctorMcKay/node-steamcommunity/wiki/CEconItem#tags
 
 
You need to get individual item from offer, and after that just call "item.tags".
Since tags is an array, you might want to use loop to check if an item contain "Craft Item"