Retrieve data from request.end() in node.js

Question

I want to use result of unirest request to another file in Node.js but I can not get data from request.end() function to outer variable.

Code is below:

request.end(function (response) {
        if(response.error) {
            console.log("AUTHENTICATION ERROR: ", response.error);
        } else {
            callback(null, response.body);
        }

        console.log("AUTHENTICATION BODY: ", response.body);
    });

var result = authentication(function(error, response) {
    var authenticationToken = response.access_token;

    if(authenticationToken != null) {
        console.log("Token: ", authenticationToken);

        return authenticationToken;
    }
});

I want to get authenticationToken value to export with module.exports for another modules.

I am using unirest http library.

Answer 1

its a callback function, and is treated as parameter, not a function that returns value.

You can do this though:

var result;
authentication(function(error, response) {
    var authenticationToken = response.access_token;

    if(authenticationToken != null) {
        console.log("Token: ", authenticationToken);

        module.exports.result = authenticationToken; // setting value of result, instead of passing it back
    }
});

you can use result variable now. But be careful, its an asynchronous function, so you may not be able to use it immediately, until a value is assigned to it, within a callback function.

To export result value:

module.exports.result = null;

Example

m1.js

setTimeout(() => {
   module.exports.result = 0;
}, 0);

module.exports.result = null;

app.js

const m1 = require('./m1.js');

console.log(JSON.stringify(m1));

setTimeout(() => {
  console.log(JSON.stringify(m1));

}, 10);

Output

{"result":null}
{"result":0}

so you can keep using variable result, once the variable is assigned it would contain the value.