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 Asynchronous Programming with JavaScript Asynchronous JavaScript with Callbacks Implement a Callback

Rye Zhu
Rye Zhu
5,514 Points
Posted by Rye Zhu
Rye Zhu
5,514 Points

Confused about this part:

Questions about this part:

btn.addEventListener('click', () => { getJSON(astrosUrl, (json) => { json.people.map( person => getJSON(wikiUrl + person.name);
}); }); });

  1. What is the json parameter?

  2. What is map?

  3. What about person? person is not a property of people.

  4. as for getJSON(wikiUrl + person.name): what's with the plus sign? I've never seen parameters separated by a plus sign in functions.

Thanks sm. I'm very confused about this chunk of code.