async.each
var arrVal = [[1,2],[[2,3],[4,5]],3,4];
var async = require('async');
var recurse = function(arr , callback) {
async.eachSeries(arr, function(eachVal, each_cb) {
if(typeof eachVal === "object") {
recurse(eachVal);
each_cb()
}
else {
console.log(eachVal);
each_cb(null);
}
}, callback);};
recurse(arrVal);