Why does this if statement not get executed?

Question

I'm trying to return the number of users that are online as determined by this JS object. However, my counter for users that are currently online never gets incremented.

I use the for-in loop to iterate through the JS object, and then I increment the 'usersOnline' variable if the specific user's 'online' property is set to true.

let users = {
  Alan: {
    age: 27,
    online: false
  },
  Jeff: {
    age: 32,
    online: true
  },
  Sarah: {
    age: 48,
    online: false
  },
  Ryan: {
    age: 19,
    online: true
  }
};

function countOnline(obj) {
  let usersOnline = 0;

  for (let user in obj) {
    if (user.online === true)
      usersOnline++;
  }

  return usersOnline;
}

console.log(countOnline(users));

usersOnline should be incremented twice so that it is equal to 2. But it stays set at 0. This problem is part of a coding challenge on freeCodeCamp.com I'm more interested in why this specific code won't work versus how to use JS objects in general.

A `for ... in` loop iterates through the **keys** of the object, not the values. — Pointy, Jun 24 '19 at 23:41
Small note: it's a bad practice to check `if (something === true)`. Instead, just check `if (something)`. — frodo2975, Jun 24 '19 at 23:47
I understand that this probably isn't the best practice for any real tasks, but I'm more interested in learning what about this specific code isn't working, I don't really need info on how to use JS objects in general. — thejacobhardman, Jun 24 '19 at 23:52
That is easily discovered by looking at the documentation for [`for...in` loops](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...in) (or even just `console.log(user)` to check its value), where you will see that it loops through the property *names*, not the property values. — Herohtar, Jun 24 '19 at 23:56
The for in loop was actually working perfectly. I just needed to go a level deeper when checking the object's values. — thejacobhardman, Jun 25 '19 at 00:18

Dacre Denny · Answer 1 · 2019-06-24T23:49:19.300

One solution would be to reduce() the values() of the users object to obtain a total number of users that are online:

let users = {
  Alan: {
    age: 27,
    online: false
  },
  Jeff: {
    age: 32,
    online: true
  },
  Sarah: {
    age: 48,
    online: false
  },
  Ryan: {
    age: 19,
    online: true
  }
};

const onlineCount = Object.values(users).reduce((total, user) => {
  /* If user is online, add 1 to the total, otherwise add 0 */
  return total + (user.online ? 1 : 0);
}, 0)

console.log(onlineCount)

The reduce() works by starting with an initial value of 0, and iterating all user values returned by Object.values(), adding a 1 or 0 to the total in order to obtain the total count of online users.

Why does this if statement not get executed?

1 Answers1