javascript - Async readFile module.exports in node.js -

i'm sorry for, might naive question, i`m trying figure out how node works, problem this:

what need send object/file fs.readfile through require , module.exports. have tried this

in 1 file (call app.js) code reading file:

var fs = require('fs'); var file_contents = undefined;  var callback_reader = function(err, data) {   if (err) return console.error(err);   file_contents = data.tostring().split('\n'); }  module.exports = {   parsefile: function(file_path) {     fs.readfile(file_path.tostring(), 'utf-8', callback_reader);   } }  

and in other file, (call main.js) need use contents of file read readfile this

var file_importer = require('./app.js') file_importer.parsefile(real_path_to_file); 

but if try console.log of last line undefined object. know because callback not execute before console.log i`m unsure how achieve communication.

so changed code little bit use callbacks. seems can't use "return" asyncronous function in module.exports. however, code bellow works expected. hope helps.

main.js

var file_importer = require('./app.js') file_importer.parsefile('./time.js', function(err, data){     if(err) return console.log(err);     console.log(data); }); 

app.js

var fs = require('fs');  module.exports = {     parsefile: function(file_path, callback) {         fs.readfile(file_path.tostring(), 'utf-8', function(err, data) {             if (err) return callback(err);             callback(null, data);         });     } }  // shorter version exports.parsefile = function(file_path, callback) {     fs.readfile(file_path.tostring(), 'utf-8', callback); }