node.js - How to return a result of async function (async module) in nodeJs -

i used async module project. code in file 1

exports.check = function(option){     var object = {};     async.parallel([         function(callback){             if(!option.one){callback(null, true);}else{ callback(null, false);}         },         function(callback){             if(!option.two){callback(null, true);}else{ callback(null, false);}         },         function(callback){             if(!option.three){callback(null, true);}else{ callback(null, false);}         }     ],     function(err, results){         if(results[0] && results[1] && results[2] ){             object.one = results[0];             object.two = results[1];             object.three = results[2];             object.total = true;          }else{             object.one = results[0];             object.two = results[1];             object.three = results[2];             object.total = false;          }     })     return object; } 

and code in file 2. use function in file 1:

var isexit = db.check(option);     console.log(isexit); 

a problem console 'undefined'. if change code in file 1 line (return object):

exports.check = function(option){     var object = {};     async.parallel([         function(callback){             if(!option.one){callback(null, true);}else{ callback(null, false);}         },         function(callback){             if(!option.two){callback(null, true);}else{ callback(null, false);}         },         function(callback){             if(!option.three){callback(null, true);}else{ callback(null, false);}         }     ],     function(err, results){         if(results[0] && results[1] && results[2] ){             object.one = results[0];             object.two = results[1];             object.three = results[2];             object.total = true;          }else{             object.one = results[0];             object.two = results[1];             object.three = results[2];             object.total = false;          }        return object;     })  } 

it error. how return funciton result in file 1. pls help. much!

you can't return it, you'll have provide callback function:

exports.check = function(option, callback){   async.parallel([     //...   ], function(err, results){     var object = {};     //...     callback(err, object);   }); } 

then call like:

db.check(option, function(isexit){   console.log(isexit); });