Things to do when we drop IE11 support someday

[jelbourn]

Writing this issue to keep track of the things we can do / drop once we no longer support IE11. This issue is mainly for record-keeping. Eventually dropping will likely be based on Microsoft ending support for Windows 7, which is currently slated for January 2020.

• Incorporate CSS custom properties into theming
• Drop extra code for sticky positioning and just use position: sticky
• Use IntersectionObserver for overlay positioning
• Use WeakSet instead of WeakMap<T, boolean>
• Second parameter to classList.toggle
• Use element.remove() instead of element.parentNode.removeChild(element)
• Start using CSS Grid, potentially deprecating mat-grid-list
• Start using KeyboardEvent.key / KeyboardEvent.code (re-evaluate cdk/keycodes)
• Explore possibly using native Shadow DOM
• Remove re-implementations of matches and closest
• Get rid of IE-specific cases in InteractivityChecker
• Explore clip-path as a means of custom shapes for components
• Remove IE11-specific fallback animation in mat-spinner
• Can use unset CSS value

[lqc]

I would like to comment on the keyCode part of the issue.

KeyboardEvent.key is widely supported. From what I could tell, Edge has fixed issues with key names (not sure about AltGr problem) and the same could be done in IE11 with a simple shim.

Would you consider going forward with dropping use of keyCode and document the shim for anyone that uses IE11 (similar to classlist, etc.) ?

[jelbourn]

Our current stance is that we don't want to require users to polyfill anything for IE11 (that isn't already needed by Angular itself).