AJAX has become very commonly used because

If $.ajax() is called with the global option set to false, the $.ajaxStart() method will not fire.

Which is true about callback function?

A callback function is a function passed as a parameter to another function.

Which is not a valid data type that AJAX expects to get from server?

Which XMLHttpRequest properties are correct?

Which is drawback of AJAX?

Which status codes denotes a server error?

Is it always possible to make requests to multiple websites with different domain names from an AJAX client script?

It might be needed to set the request content-type to XML explicitly. How can you do so for an XMLHttpRequest Object?

Which is a block comment in JavaScript?