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 AJAX Basics (retiring) Programming AJAX Create a callback

Posted by liamthornback2
liamthornback2
9,618 Points

why does the editor not accept xhr.onreadystatechange(() => { }); ?

Does the editor not like anonymous functions?

I also tried xhr.onreadystatechange(function() { }); and it didn't like that either

app.js 
var xhr = new XMLHttpRequest();
xhr.onreadystatechange(
  function() {
  }
);
xhr.open('GET', 'sidebar.html');
xhr.send();
index.html 
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>AJAX with JavaScript</title>
  <script src="app.js"></script>
</head>
<body>
  <div id="main">
    <h1>AJAX!</h1>
  </div>
  <div id="sidebar"></div>
</body>
</html>

1 Answer

James Anwyl
.a{fill-rule:evenodd;}techdegree seal-36
James Anwyl
Full Stack JavaScript Techdegree Graduate 49,960 Points

Hi Liam,

It's because you are trying to pass the anonymous function to xhr.onreadystatechange, as if it's a parameter.

You need to assign the function to xhr.onreadystatechange using =

For example:

xhr.onreadystatechange = function(){};

Hope this helps :)

liamthornback2
liamthornback2
9,618 Points

Thank you very much.