foo.js

var async = require('async');

(function () {
    var tmp;
    async.series(
        [
        (cb) => { console.log("1"); tmp = "foo"; cb(null, "result1"); },
        (cb) => { console.log("2"); cb(null, tmp + " result2"); },
        ],
        (err, results) => { console.log("result: " + results); }
    )
})();