[Regression] default AJAX links break in IE11

Just making notes to gauge the urgency of fixing this

https://www.w3counter.com/globalstats.php

Suggests IE11 has 3.16% global usage.

In my experience w3counter has a bias, other global stats produce different results, but all within a margin
suggesting IE11 is on its way out.

Drupal8 at time of writing supports IE11!

https://www.drupal.org/docs/8/system-requirements/browser-requirements

As reported by Matroskeen, here

https://www.drupal.org/project/flag/issues/2764709#comment-12502502

Syntax error is in this line:

attach: context => {

and in this construction: =>

Please see https://stackoverflow.com/a/24900924/6314031.

looking at the error message in #4 and in core for the standard way to "attach" in es6 code... I see I was doing it wrong...

./core/modules/editor/js/editor.es6.js

  /**
   * Enables editors on text_format elements.
   *
   * @type {Drupal~behavior}
   *
   * @prop {Drupal~behaviorAttach} attach
   *   Attaches an editor to an input element.
   * @prop {Drupal~behaviorDetach} detach
   *   Detaches an editor from an input element.
   */
  Drupal.behaviors.editor = {
    attach(context, settings) {
      // If there are no editor settings, there are no editors to enable.
      if (!settings.editor) {
        return;
      }

I note that flag-admin.js follows the old way of doing it ... but uses strict mode.

I am not a IE11 user so I hope this fixes the problem?

transpiling is supposed to remove all these incompatibilities. --- presets can describe which browsers we target.
... here is a code snippet.

"presets": [
    "es2015",
    "react",
    "next/babel",
    "stage-0",
    [ "env", {
      "targets": {
        "safari": 10,
        "ie": 11
      },

BUT in this module the js is only a small part of the project... so overall I think we gain most advantage by keeping in lock step with D8 core.... in that vein we inherit all the inconsistencies of the larger project. I will look at this further tonight.

There are several takes on the fix for this... all roads lead back to "I was an idiot"

Doh -- Drupal8 core does have build targets... it builds for "ie >= 9"
Doh -- The fix - We should be in lock step with core.
Doh -- now we implement "transform-es2015-arrow-functions"

So the fix: put package.json in lock step with core and retranspile.

[Me: hang head in shame and eats donuts ]

Regarding #9

While I have never met socketwench, I have seen the way she forms arguments in the issue queue, and have seen her contribution to the module.... in short that is a major failure on my part. I am spinning off an issue "write a welcoming developer guide for coders with far less experience"

It may also be my fault in another way ... so I am going to iron out a quirk which potentially stops others from building the javascript. Following on my "we should keep in lock step with core" track ... I note that core does not commit package-lock.json... it will be automatically populated as part of the "install the programs for transpiling" of any good guide.

@Matroskeen .. I will have a look at #10 tonight.

I have just reread #11 I meant only to imply that socketwench has loads of experience and I want to provide a on ramp for all developers ... that did not jump of the page due to my clumsy word salad... sorry