Using "Event" constructor should be replaced by "CustomEvent" constructor? (IE11 compatibility)

[jybleau]

Firstly, I can create a PR if you want...

I have a problem with those lines in IE11:

pnotify/packages/core/index.svelte

Line 112 in e63f4c8

const event = new Event('pnotify:position');

pnotify/packages/core/index.svelte

Line 394 in e63f4c8

const eventObj = new Event(`pnotify:${event}`, {

There is a bug when including @pnotify/core/dist/PNotify.js :
Calling new Event(...) fails and it seems it's not safe/recommended to replace it with a polyfill directly... (Some say yes, some say no; MDN does not suggest to do so...)

Instead of trying to transpile (if it would rewrite this code correctly?), I found out we should instead be creating an event using the new CustomEvent(...) constructor
Ref to the API:
https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/CustomEvent

This API does not exists in IE11 but then it can be safely added as a polyfill as described in the MDN Web Docs, and it works fine.

PS: If I understand correctly your README file, the dist/Pnotify.js can be used in ES5 browsers. And I already include es5 and es6 shims in my projects and Pnotify is working fine so far when combined with the use of CustomEvent API and a polyfill of course.

PS2: Another related issue: Setting the Event.detail property after the event has been created is not suppose to work in strict mode (it is supposed to be a RO property); it should instead be included with the parameters in the call to the contructor.
here:

pnotify/packages/core/index.svelte

Line 398 in e63f4c8

eventObj.detail = eventDetail;

And here is how I modified the code:
jybleau@f3ef80f

Anyway, what do you think about that?

Thanks