Basic Data Structures - Iterate Through the Keys of an Object with a for...in Statement

JavaScript
1

Tell us what’s happening:
I’m doing the for in loop and I tested my code in Codepen and the result counts 0,1,2,3 as intended when I directly use “users” as the object literal instead of the parameter “usersObj”.

Although the the fcc console only accepts usersObj[names].online

  **Your code so far**

const users = {
Alan: {
  online: false
},
Jeff: {
  online: true
},
Sarah: {
  online: false
}
}

function countOnline(usersObj) {
// Only change code below this line
let i = 0;
for (let names in users) {
if(users[names].online === true) {
  i++;
}
}
return i;
// Only change code above this line
}

console.log(countOnline(users));

  **Your browser information:**

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

Challenge: Basic Data Structures - Iterate Through the Keys of an Object with a for…in Statement

Link to the challenge:

1 Like
2

yes, because your function should be reusable. if you use usersObj it’s reusable and can be used with different objects

3

Let’s say you want to run this code

const randomObj1 = {sam:{online:true}, max:{online:true}}
const randomObj2 = {sam:{online:false}, max:{online:true}}
countOnline(randomObj1)
countOnline(randomObj2)
countOnline(users) //(users is your object)

How do you make the function succeed at logging each online count ?

1 Like
4

Use argument for different objects.
Although I understand that the real world would only have one name per user that’s probably why I didn’t pay attention to the re-usability.

But I do understand the applicability of using the argument instead of the object name now.

Thankyou.

5

An important concept is the parameters here. If the object is always “users”, the function does not need a parameter in the definition.

To be precise:

function countOnline() {
//...
}

That would be equivalent. But it is not what we want/ We want an argument to reuse it, and also to isolate that functionality etc.

6

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