Node.js export variable

Question

I am writing a Node.js module and I need to pass variable data from the main file to the functions. I am doing this:

var region;
var api_key;

exports.region = region;
exports.api_key = api_key;


module.exports = {

  getSummonerId: function(sum, callback) {

    var summoners = {};
    var summoner = sum.replace(/\s+/g, '');

    request("https://na.api.pvp.net/api/lol/" + region + "/v1.4/summoner/by-name/" + summoner + "?api_key=" + api_key, function(error, response, body) {
      summoners[summoner] = JSON.parse(body);
      callback(summoners[summoner][summoner].id);
    });
  }
}

And in the main file:

var lol = require('./apiwrapper.js');

lol.api_key = "example";
lol.region  = "las";


lol.getChampions(function(data) {
  console.log(data);
})

But from apiwrapper.js file, those two variables' value are always "undefined".

How can I fix this?

You cann't use exports.region and module.exports at the same time. — BlackMamba
– BlackMamba, Commented Dec 23, 2014 at 4:21

Felix Kling · Accepted Answer · 2014-12-23 05:01:35Z

13

The value that is imported to the other module is module.exports. So, what you assign to module.exports is exported. Whatever was assigned earlier to it is lost.

The relation between module.exports and exports is that they refer to the same object initially:

var exports = module.exports = {};

So, assigning a property to either of them mutates the same object. However, you are assigning a new object to module.exports, so now both of them reference different objects.

A simple solution is to assign the new object to exports as well and then assign the other properties:

exports = module.exports = {...};
exports.region = region;

If you want to keep the order of the statements, then you have to extend the default exports object, instead of creating a new one:

Object.assign(exports, { ... });

answered Dec 23, 2014 at 5:01

Felix Kling

820k181 gold badges1.1k silver badges1.2k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Peter Mortensen · Accepted Answer · 2020-10-03 23:49:19Z

1

Use:

module.exports = {
  region: my_region,
  api_key: my_api_key,
  getSummonerId: function(sum, callback) {

    var summoners = {};
    var summoner = sum.replace(/\s+/g, '');

    request("https://na.api.pvp.net/api/lol/" + region + "/v1.4/summoner/by-name/" + summoner + "?api_key=" + api_key, function(error, response, body) {
          summoners[summoner] = JSON.parse(body);
          callback(summoners[summoner][summoner].id);
    });
  }
}

In your case, "module.exports" is overwriting the previously exported variables. Which is the reason you are getting undefined for those.

edited Oct 3, 2020 at 23:49

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered Dec 23, 2014 at 5:23

Rana

6,20414 gold badges61 silver badges91 bronze badges

1 Comment

Rana Over a year ago

yup, exactly. Just try it!

Collectives™ on Stack Overflow

Node.js export variable

2 Answers 2

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related