Iterate Through the Keys of an Object with a for...in Statement HELP PLEASE

JavaScript
1

Tell us what’s happening:
I can"t figure out where i am mistaking. Is my variable ‘user’ directly refer to my user’s name when i declare it? (Despite the fact i didnt mention something like user = “Alan”, “Ryan” etc…

Your code so far

 let usersOnline = 0;
for (let user in users) {
  if (users.user.online == true) {
    userOnline++
  }
  return userOnline
}


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) {
  // change code below this line
  let usersOnline = 0;
for (let user in users) {
  if (users.user.online == true) {
    userOnline++
  }
  return userOnline
}
  // change code above this line
}

console.log(countOnline(users));

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Firefox/68.0.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-data-structures/-iterate-through-the-keys-of-an-object-with-a-for---in-statement

2

first, you should use the function parameter, so you should do obj.user.online and let user in obj, so to make your code reusable

second, you can’t use dot notation with variables, as dot notation try to access a property with that exact name

3

Thanks for your answer;
So i should have use bracket notation?

 if (user["online"] == true])

I teste the above, but it returns me : “online is not defined”

I have to admit im kind of lost here…

4

user is a string, it doesn’t have properties

you are correct that you need to use bracket notation, but for online is not needed, you can access the property online with dot notation as that is the literal name of the property
you have removed a real important piece now

5

Thanks for answering, but im still confused. Which important part did i removed? Where to use bracket notation if not on my property ? Argh !

My code so far :

let usersOnline = 0;
for (let user in obj) {
  if (users['user'].online == true) {
    usersOnline++
  }
  return usersOnline
}
6

that’s better… but does the users object has a property called user? no, it doesn’t
remember the difference between a string and a variable

7

But im confused when you say that user is a string, because to me it is a variable, which i have declared in my for loop. Though, i agree that user is not a property from user. So i understand why it doesnt worck. Im still unable to understand how to navigate through users, to check every name…

8

you can’t do this because user has the value of a string, so it can’t have a property

you can’t do this because you are losing the variable

users is an object, it has many properties, at each iteration of the loop, user has the value of one of those property names. so you need to use bracket notation to access the nested objects which are the values of the properties of user

9

You are right, user is a variable, not a string, and at each iteration a string was assigned to the variable user (for example at the beginning of the first iteration the string “Alan” is assigned to to the variable user).

In your code the problem is that you are not using the variable user, instead you are using the string ‘user’:

 users['user'].online == true

So to fix your code user must be a variable, not a string.

10

Ok so i end up my reflexion with :

  if (users.user["online"] == true)

but it returns me users.user undefined.

It seems like both of you are giving me the good advices, but i still can’t figure out by myself how to fix my code.

11

user is a variable
but if you try to do users.user your re trying to access the property named user, not named as the value that the user variable holds

you can’t use dot notation with variables because they are not evaluated to the value they hold

for a variable to be evaluated you need to use bracket notation

remember this challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-javascript/accessing-object-properties-with-variables