xhr library Null safety

XMLHttpRequest Standard

https://xhr.spec.whatwg.org/

Classes

FormData
The interface provides a way to easily construct a set of key/value pairs representing form fields and their values, which can then be easily sent using the XMLHttpRequest.send() method. It uses the same format a form would use if the encoding type were set to "multipart/form-data". [...]
ProgressEvent
The interface represents events measuring progress of an underlying process, like an HTTP request (for an XMLHttpRequest, or the loading of the underlying resource of an <img>, <audio>, <video>, <style> or <link>).
ProgressEventInit
XMLHttpRequest
(XHR) objects are used to interact with servers. You can retrieve data from a URL without having to do a full page refresh. This enables a Web page to update just part of a page without disrupting what the user is doing. is used heavily in AJAX programming. [...]
XMLHttpRequestEventTarget
is the interface that describes the event handlers you can implement in an object that will handle events for an XMLHttpRequest.
XMLHttpRequestUpload

Enums

XMLHttpRequestResponseType