Increment number with true and false

[E1cid]

Not sure what msg.topic is, as htbset is a count.
something like below should work to increment/deincrement the count

if (typeof(msg.payload)==="boolean"){ // payload has to be true or false
    var hbtset = flow.get("hbtset") || 0; //fetch count or default 0
    if (msg.payload === true) {
        hbtset++; // if true plus 1
    }else{
        hbtset--; //if false minus 1
    }
flow.set("hbtset", hbtset)  // save count
}
return msg;