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 What is Asynchronous Programming? Examples of Synchronous and Asynchronous Code

HsinTzu Chen
HsinTzu Chen
5,833 Points
Posted by HsinTzu Chen
HsinTzu Chen
5,833 Points

Does send(null) had impact on asynchronous behavior?

I think the synchronous and asynchronous behaviors in first and second example is made by third argument in open method (true: asynchronous or false: synchronous).

However, there is also difference in send method first example (synchronous )-->xhr.send(null) and second example (synchronous )-->xhr.send().

I am wondering if null argument has impact on asynchronous behavior? If not, does anyone knows why null argument is used? Many Thanks!

2 Answers

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

If you look at the MDN documentation for xhr.send(), you'll find that it says "If no value is specified for the body, a default value of null is used."

So it's simply programmer's preference, either an empty argument or an explicit null will produce the same behavior.

HsinTzu Chen
HsinTzu Chen
5,833 Points
HsinTzu Chen
HsinTzu Chen
5,833 Points

Steven Parker , I see. Next time, I will try to check official document first. Thank you for your explanation!