Currently the FormData API is only partially implemented in Edge. Most of the more useful methods are missing including: has(), get(), set(), delete(), entries(), and many others.

FormData is already fully implemented on the other major browsers (Firefox, Chrome, Safari) - see: https://developer.microsoft.com/en-us/microsoft-edge/platform/catalog/?q=formdata

Please support BigInt, a stage-3 proposal. https://tc39.github.io/proposal-bigint/

https://www.w3schools.com/jsref/met_number_stepup.asp
https://www.w3schools.com/jsref/met_number_stepdown.asp

These are currently not supported by Edge.

They work fine for range or date input, but someone just missed the most natural use of these methods for number input.

Async iterators and async generator functions(https://github.com/tc39/proposal-async-iteration) are now a stage-3 ECMAScript proposal, nearly finished. They make many styles of programming in JavaScript easier (https://ponyfoo.com/articles/javascript-asynchronous-iteration-proposal); in particular, they are important for WHATWG Streams (https://streams.spec.whatwg.org). As of 2017-10-22, async generators have already been implemented in Blink, Firefox, and WebKit.

Pretty print no longer works with large JS files in the latest updates. I thought it was completely broken, but for small files it works fine. Please fix, this is making hard to justify using Edge when I can't debug.

An API that returns a map which translates from `KeyboardEvent.code` values into a strings that can be shown to the user to identify each key.

This is not possible with existing web platform APIs because the value that should be shown to the user depends on the keyboard layouts that the user has installed and active.

WICG incubation spec: https://wicg.github.io/keyboard-map/

Note: there is some overlap between this and a previous feature request https://wpdev.uservoice.com/forums/257854-microsoft-edge-developer/suggestions/6508637-uievents-keyboard-query-apis

The previous request was based on an old proposal that is no longer being pursued in the standards bodies.

The Web Crypto API is not available inside a Web Worker. Both "self.crypto" and "self.msCrypto" are undefined inside a worker context.

IE support only basic feature of IndexedDB specification http://www.w3.org/TR/IndexedDB/. Data intensive web app using full specification are not able to run on IE. Specifically missing feature are compound index, complex key path, multiEntry index and storing blob.

BroadcastChannel offers a way for all scripts, regardless of window/frame/tab/worker context, to communicate with each other via messaging, similar to MessageChannel.

A message sent via BroadcastChannel is delivered to all environments running with the same origin as the sender.

Besides providing better tools for JS devs, this will greatly enhance JavaScript's support for functional languages compiled to JS, like ClojureScript.

Defines an API supporting the MIDI protocol, enabling web applications to enumerate and select MIDI input and output devices on the client system and send and receive MIDI messages.

http://webaudio.github.com/web-midi-api/

CSS Font Loading API

Encode audio and video streams in the browser.

Spec: http://www.w3.org/TR/mediastream-recording/

Enables web developers to incorporate speech recognition into their web pages.

https://dvcs.w3.org/hg/speech-api/raw-file/tip/speechapi.html

Adding support for the full WebWorker API (Worker, SharedWorker, and Nested Workers).

The Network Information API provides information about the system's connection, which is in term of general connection type (e.g., 'wifi', 'cellular', etc.). This can be used to select high definition content or low definition content based on the user's connection. The entire API consists of the addition of the NetworkInformation interface and a single property to the Navigator interface: Navigator.connection.
http://w3c.github.io/netinfo/

Namely TextEncoder and TextDecoder

Spec: https://encoding.spec.whatwg.org

Change your implementation of Array.sort to be stable.

Edge is now the only browser vendor that does implement a stable sort. Chrome recently switched their sort to be stable. (https://stackoverflow.com/a/52151900)

Use case: A stable sort is really important for browsers because so much of what they're sorting is for UI display purposes. Users don't like it when sorting a grid by a certain column and "equal" rows randomly resort if the grid decides to resort them.

A implementation of the ResizeObserver API would be nice.

Explainer: https://github.com/WICG/ResizeObserver/blob/master/explainer.md
Spec: https://wicg.github.io/ResizeObserver/

Thanks!