xhr.send should test if data property is undefined

[rschouten]

When using the $.ajax method with type 'POST' or 'DELETE' (probably other types too) and the data property is undefined, the string "undefined" appears in the request's payload. Normally this does not matter but in certain circumstances,like working with 3rd party APIs, this can lead to errors.

If sending 'undefined' as a string is not intentional, the data property should be tested and only sent if it is defined.

For example, at line 3633 of file ​http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.js the code could be changed to:

if (s.data === undefined) {

xhr.send();

} else {

xhr.send(s.data);

}

[dmethvin]

Fixed in 1.4.3