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JavaScript

Posted by Chigozie Beluolisa
Chigozie Beluolisa
16,263 Points

HELP ! ! Can't return a Variable in an Anonymous function scope in Node.js

Hello Developers,

Please i am trouble trying to return the variable(profile) in the get(username) function. I have tried setting profile as a global variable but it doesn't seem to work. Please see script below for more details :)

Thanks in anticipation of your feedback !!

//Problem: Can't return variable(profile) in an annonymous function

var http = require("http");

//Print out message
function printMessage(username, badgeCount, points) {
  var message = username + " has " + badgeCount + " total badge(s) and " + points + " points in JavaScript";
  console.log(message);
}

//Print out error messages
function printError(error){
    console.error(error.message);
}

function get(username){
  //Connect to the API URL (https://teamtreehouse.com/username.json)
  var request = http.get("http://teamtreehouse.com/" + username + ".json", function(response){
    var body = "";
    //Read the data
    response.on('data', function (chunk) {
      body += chunk;
    });
    response.on('end', function(){
      if(response.statusCode === 200) {
        try {
            //Parse the data
            var profile = JSON.parse(body);
            //Print the data
            printMessage(username, profile.badges.length, profile.points.JavaScript);
             console.log("variable profile in anonymous function scope is",profile);
        } catch(error) {
          //Parse Error
          printError(error);
        }
      } else {
        //Status Code Error
        printError({message: "There was an error getting the profile for " + username + ". (" + http.STATUS_CODES[response.statusCode] + ")"});
      }
    });
  });

  //Connection Error
  request.on("error", printError);


  //Can't return variable profile
 // variable (profile) is stored in the anonymous function scope
// where the JSON data is parsed
  console.log(profile);
  return profile;

}



var profile = get("chalkers");

3 Answers

Hugo Paz
Hugo Paz
15,622 Points
Hugo Paz
Hugo Paz
15,622 Points

Hi Chigozie,

looking at your code, it seems you are not saving the return anywhere.

Try this:

var profile = get("chalkers");
Chigozie Beluolisa
Chigozie Beluolisa
16,263 Points

Thanks HugoPaz for your swift response. I have tried it and it doesn't seem to work. It looks like the variable (profile) in the anonymous function becomes undefined outside the anonymous function scope. So it ends up returning undefined

Sean T. Unwin
Sean T. Unwin
28,690 Points
Sean T. Unwin
Sean T. Unwin
28,690 Points

It is failing at line 49, because when you call profile there it is outside the scope of where var profile was declared. This is an example of Encapsulation.

If you move that code to line 31, i.e subtitute the console.log() statement that is already there so it's more descriptive it will output:

// Line 31
// Change
console.log(profile);
// To
console.log("The data in variable profile is",profile);
// I know it's the same thing basically,
// but we're making the output more relatable.

By the way, outputting profile will be quite long and the beginning may get cut off by your console.

Chigozie Beluolisa
Chigozie Beluolisa
16,263 Points

Thanks for your answer Sean T. Unwin . it looks like the variable profile is private in the annonymous function. My goal is to make it public so that i can return it at the end of the function call.

Sean T. Unwin
Sean T. Unwin
28,690 Points

The code above I posted is at the end of the function call. I can understand how it doesn't feel like it, but it is because the `response.on('end') happens at the end of the AJAX request.

If you try to do it at the end of the code for the get() function it's not really the end, it's near the beginning sort of since get() is waiting for response object to return.

Lemuel Ambie-Barango
Lemuel Ambie-Barango
31,559 Points
Lemuel Ambie-Barango
Lemuel Ambie-Barango
31,559 Points

Hi Chigozie,

Since you have a 'try/catch' block. I will suggest that you print and return the profile in the try block and set the profile to nil and return in the catch block so if there's an error it will set the profile as nil and print the error.

        try {
            //Parse the data
            var profile = JSON.parse(body);
            //Print the data
            printMessage(username, profile.badges.length, profile.points.JavaScript);
            console.log(profile);
            console.log(username);

            //Can't return variable profile
            console.log("The data in variable profile is",profile);
            return profile;
        } catch(error) {
          //Parse Error
          printError(error)

          var profile = ' ';
          console.log("The data in variable profile is",profile);
          return profile;
        }
Sean T. Unwin
Sean T. Unwin
28,690 Points

I have edited your post so that the code is more readable.

Please see this thread if you need help posting code snippets.