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

Mayank Munjal
.a{fill-rule:evenodd;}techdegree seal-36
Mayank Munjal
Front End Web Development Techdegree Graduate 18,120 Points

So xhr.onreadystangechange is the callback function but I'm getting confused as to when it is called back?

I don't see a higher order function using the callback function as an argument so if someone can explain what's going on, it will help a lot!

1 Answer

Steven Parker
Steven Parker
228,095 Points

The callback function is used by an internal event handler that is established by the "xhr.send()" call. It accesses the callback directly as a property of the "xhr" object instead of having it passed as an argument.