Update ProgressEvent to use double type for 'loaded' and 'total'

Category: JavaScript
Type: New or changed feature
Status: Proposed (Chrome Proposed)
Intent stage: None

Breaking change: No
Enterprise impact: Low
Spec maturity: Unknown status
Web Platform Tests: Yes

WPT details: https://wpt.fyi/results/xhr/progress-events-response-data-gzip.htm?label=experimental&label=master&aligned https://wpt.fyi/results/xhr/progressevent-constructor.html?label=experimental&label=master&aligned https://wpt.fyi/results/xhr/progressevent-interface.html?label=experimental&label=master&aligned

Summary

The ProgressEvent has attributes `loaded` and `total` indicating the progress, and their type is `unsigned long long` now. With this feature, the type for these two attributes is changed to `double` instead, which gives the developer more control over the value. For example, the developers can now create a ProgressEvent with the `total` of 1 and the `loaded` increasing from 0 to 1 gradually. This is aligned with the default behavior of the <progress> HTML element if the max attribute is omitted.

Motivation

https://github.com/webmachinelearning/writing-assistance-apis/issues/15

Standards & signals

Specification: https://whatpr.org/xhr/394.html#interface-progressevent
Firefox: Positive
Safari: Positive
Web developers: Positive

Ecosystem

Web Platform Tests: https://wpt.fyi/results/?q=xhr%2Fprogress-events-response-data-gzip
Chrome Platform Showcase: https://chrome-platform-showcase.paulkinlan-ea.deno.net/features
GenDN reference: https://gendn.paulkinlan-ea.deno.net/features
chrome.dev demos search: https://www.google.com/search?q=site%3Achrome.dev+Update%20ProgressEvent%20to%20use%20double%20type%20for%20'loaded'%20and%20'total'
MDN Web Docs: https://developer.mozilla.org/en-US/search?q=Update%20ProgressEvent%20to%20use%20double%20type%20for%20'loaded'%20and%20'total'
Baseline status: https://webstatus.dev/?q=Update%20ProgressEvent%20to%20use%20double%20type%20for%20'loaded'%20and%20'total'

Explainers: https://github.com/whatwg/xhr/pull/394

View on chromestatus.com