Nodejs Unused callback

nodejs-unused-callback.js

var async = require('async')

var counter = 0

async.series([
        function(callback) {
                async.whilst(
                        function() { return counter < 5; },
                        function(whilstCallback) {
                                console.log('tick %d', counter)
                                ++counter
                
                                if(counter == 3)
                                        return callback();
                
                                setTimeout(whilstCallback, 1000)
                        },
                        function() {
                                console.log('counter %d', counter)
                        }
                )
        }
], function() {
        console.log('series done')
})