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JavaScript AJAX Basics (retiring) AJAX Concepts A Simple AJAX Example

Steve Fan
Steve Fan
8,218 Points
Posted by Steve Fan
Steve Fan
8,218 Points

Why it response when it hold the number 4

It mentioned that when it hold 4, it will response. And the syntax is: if (xhr.readyState === 4)

Could someone explain why the value is 4 but not anything else?

1 Answer

Umesh Ravji
Umesh Ravji
42,386 Points
Umesh Ravji
Umesh Ravji
42,386 Points

In short the readyState property changes from 0, 1, 2, 3, then 4 from the beginning (before request sent) to 4 at the end meaning that the request has been completed. A value of anything less than 4 means that the request hasn't been completed yet.

If you want to read more into what the different numbers mean check out these docs: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/readyState

Steve Fan
Steve Fan
8,218 Points
Steve Fan
Steve Fan
8,218 Points

Thank man, I got it.