json - How to pass value of object to new global variable in JavaScript -

i have written program run node.js server interact python script (source: https://github.com/extrabacon/python-shell), sends data script , receieves returned value. returned (message) (in pyshell.on) json, appears local function passed in, use data elsewhere in program outside function.

being new javascript tried set ret_val = message; no avail, have tried changing type (python side) string (still no success), , converting json string , parsing ret_val (as now) ret_val = json.parse(json.stringify(message));. unfortunately none of these methods work, ret_val remains undefined, despite message containing data need object (checked using typeof). know either correct way copy contents of message variable ret_val later returned, or possibly correct way message data if using module incorrectly.

see below logs

update: full script containing issue, occurs in function run_py_script when setting ret_val.

var express = require('express'); var router = express.router(); var pythonshell = require('python-shell');  var options = {     mode: 'json' };  var rain_data;  function run_py_script(data, callback){     var pyshell = new pythonshell('dummy.py', options);     var ret_val;     pyshell.send("dummy data"); // change data      pyshell.on('message', function(message){         console.log(message);         rev_val = message;         //console.log(ret_val["willcollide"]);     });      pyshell.end(function(err){         if (err) {             console.log("hi");         }         return err ? callback(null) : callback(null, ret_val);     });  }  /* rain_track data. */  router.get('/', function(req, res, next) {      run_py_script(null, function(err, rain_data) {         console.log(err);         console.log(rain_data);         if (err){ console.log("error in python script" ); return res.json(null); }         if (rain_data == null){             console.log("error: data null or undefined");         }         res.json(rain_data);     }) });  module.exports = router; 

logs:

{ willcollide: 1, time: 6000, strength: 'na' } null undefined error: data null or undefined /rain_track 200 62.778 ms - -