It’s necessary to write a function for creating new
XMLHTTPRequest objects, because
Microsoft browsers use two different methods of creating them,
while all other major browsers use a third. By writing a function
to test the browser in use, you can ensure that code will work on
all major browsers.
The purpose of the
try...catch construct is to set an error
trap for the code inside the
try statement. If the code causes an
catch section will
be executed instead of a general error being issued.
You can tell that an Ajax call has completed when the
readyState property of an
object has a value of 4.
When an Ajax call successfully completes, the object’s
status will have a value of
contains the value returned by a successful Ajax call.
contains a DOM tree created from the XML returned by a successful
To specify a callback function to handle Ajax responses,
assign the function name to the
onreadystatechange property. You can
also use an unnamed, inline function.
To initiate an Ajax request, an
send method is called.
The main differences between an Ajax
POST request are that ...