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

Abe Layee
Abe Layee
8,378 Points
Posted by Abe Layee
Abe Layee
8,378 Points

Please explain " for in" loop to me.

Good day. I am confused with the for in loop. Even though I passed the challenge, I don't feel like I understand it well. I understand the basic of creating an object, but accessing the values with 'for in' is what I don't understand. Can anyone please explain this 'for in' to me. I appreciate it and thank you

var shanghai = {
  population: 14.35e6,
  longitude: '31.2000 N',
  latitude: '121.5000 E',
  country: 'CHN'
};
for (var key in shanghai) {
  console.log(key, ':' ,shanghai[key]);
}

1 Answer

rydavim
rydavim
18,813 Points
rydavim
rydavim
18,813 Points

I find it helpful to read it like, [for] each property [in] this object, do something. You could achieve the same effect using a regular for loop, for in is just an easy way to iterate over the properties.

So in this case you're saying [for] each property [in] the shanghai object, print the key and value pair with a : in between.