IE 11 support

[jameswragg]

Realising a little late in the day that this library only supported IE 11 in the 3.x branch. I'm using the current 4.x release due to being able to apply install on an existing iframe - functionality required for my project 😫.

Before I dive in to it, is IE 11 support a matter of transpiling/polyfilling or is it entirely incompatible?

Thanks in advance

[Aaronius]

Hey @jameswragg, I haven't tried running it on IE since 3.x, so I'm not sure how far off it is. If I were to guess, there's probably very little that needs to change beyond transpilation. If you find out, I'd be interested in knowing.

I noticed a fork of Penpal that has a commit that appears to be supporting IE: holidaycheck@1167808 By looking at the changes to the files in src, it looks like a couple very small tweaks.

[jameswragg]

Really useful - thank you!

[Aaronius]

@jameswragg If you've investigated this further, I'd like to hear about what you discovered.