Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects Accessing All of the Properties in an Object

tako izu
tako izu
15,284 Points

I don't think this is working...

On here, I've used the same code as the teacher in the video to access all the property names. I don't know why this isn't working, but if something's wrong, please tell me :)

script.js
var shanghai = {
  population: 14.35e6,
  longitude: '31.2000 N',
  latitude: '121.5000 E',
  country: 'CHN'
};

for (prop in shanghai) {
  console.log(prop);
}
index.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript Objects</title>
</head>
<body>
<script src="script.js"></script>
</body>
</html>
tako izu
tako izu
15,284 Points

Also, this is what comes up: Bummer: There was an error with your code: ReferenceError: Strict mode forbids implicit creation of global property 'prop'

1 Answer

Antony .
Antony .
2,824 Points

The solution to your issue is to assign the keyword const to props, but I also suggest you to read this Medium post.

Upon deeper inspection of these types of for loops, it seems that they create a new block scope with each iteration. That would mean that each new index is actually a new variable within a new scope & our constant is never reassigned.

for (const prop in shanghai) {
  console.log(prop);
}