JSON variable returns Undefined

Question

Sorry for the inconvenience, I am a newbie in Node. I am trying to store a json in "usersData" variable so I want to use it later in another functions. The problem is that if I test the variable with console.log inside the "if" it returns to me results, but when trying to show the variable outside the request subfunction, it comes out 'undefined'. I have declared the global usersData variable as shown below. Thank you.

var usersData;

function getAllUsers(){
  request({url, json: true}, function (error, response, body) {
    if (!error && response.statusCode == 200) {
      usersData = body
      //console.log(usersData)  //Here returns a value
    }
  });
  console.log(usersData)  //here returns undefined
}

Answer 1

request is asynchronous method, so if you want to use its result later in another functions, should handle that in second parameter callback. i.e

var usersData;

var handleUserData = function() {};

function getAllUsers(){
  request({url, json: true}, function (error, response, body) {
    if (!error && response.statusCode == 200) {
      usersData = body
      //console.log(usersData)  //Here returns a value

      // use results in another function
      handleUserData(body);
    }
  });
}

or use Promise

function getAllUsers() {
  return new Promise(function(resolve, reject) {

    request({url, json: true}, function (error, response, body) {
      if (!error && response.statusCode == 200) {
        usersData = body
        //console.log(usersData)  //Here returns a value
        resolve(body);
      } else {
        reject(error);
      }
    });

  });
}

// handle `usersData`
getAllUsers().then(body => {
  handleUserData(body);
});