How to avoid access mutable variable from closure

Question

I have some code like this:

for(var id=0; id < message.receiver.length; id++){
   var tmp_id = id;
   zlib.gzip(JSON.stringify(message.json), function(err         


        

Answer 1

here a simplification of user24359's great answer. This is the solution:

var object = {a:1,b:2};

for (var y in object){
    (function(){const yyy = y;
        setTimeout(function(){console.log(yyy)},3000);})();
}

The above code logs a b and is the solution. The following code logs b b :

var object = {a:1,b:2};
for (var y in object){

    setTimeout(function(){console.log(y)},3000);
}