fix: Support experimental copy & paste in IE 11

[SilentGert]

Fixes #348

I added a fallback to use window.clipboardData when event.clipboardData is not defined, which is the case in IE 11, when the new experimental copy and paste feature is used.

Following the investigation in this PR, I disabled the new cut, copy, paste mechanism for browsers whose events do not have clipboardData attached to the event. This concerns mostly IE.

In IE 11 the clipboardData object is attached to window and only supports mime type text. Therefore, the new mechanism will not work anyway as it makes use of two different mime types.

How to test?

1. Open IE 11
2. Go to https://react-mentions.wolf-pack.now.sh
3. Scroll to the EXPERIMENTAL section
4. Copy the text with mentions
5. Paste it in the next input

[vercel]

This pull request is automatically deployed with Now.
To access deployments, click Details below or on the icon next to each push.

Latest deployment for this branch: https://react-mentions-git-bugfix-348-copy-and-paste-ie11.wolf-pack.now.sh

[SilentGert]

Okay, just adding the fallback doesn't solve the problem. Now I'm running into other error message when accessing setData and getData.

[SilentGert]

It looks like IE 11 has a problem with the formats text/react-mentions and text/plain. Just using text as format doesn't throw any errors.

While looking for more details about the problem I found this ticket: ProseMirror/prosemirror#325

It looks like we would need some extra handling to support the new feature in IE 11.
Even if you look at libraries like https://github.com/sudodoki/copy-to-clipboard they have no special handling for the format.

Now that makes me wonder if we should just disable the feature for IE 11 by checking for the existence of clipboardData:

handleCopy(event) {
    if (event.target !== this.inputRef) {
      return
    }
    if (!event.clipboardData) {
      // In case of IE 11 or older which do not support copying different formats
      return
    }

Then we stick to the browsers default behaviour for now.

@frontendphil @jfschwarz Any opinion?

[codecov-io]

Codecov Report

Merging #349 into master will increase coverage by 0.29%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #349      +/-   ##
==========================================
+ Coverage   76.82%   77.11%   +0.29%     
==========================================
  Files          22       22              
  Lines         630      638       +8     
  Branches       95       98       +3     
==========================================
+ Hits          484      492       +8     
  Misses        145      145              
  Partials        1        1

Impacted Files	Coverage Δ
src/MentionsInput.js	67.91% <100%> (+0.75%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3c69008...b2b7d1a. Read the comment docs.

[frontendphil]

I think aiming for modern browsers and ditching IE 11 is ok 👍