Errors for IE users in Japan

• SystemJS Version:
• Which library are you using?
  • system.js
  • s.js
  • system-node.cjs
• Which extras are you using?
  • AMD extra
  • Named Exports
  • Named Register
  • Transform
  • Use Default
  • Global
  • Dynamic Import Maps
• Are you using any custom hooks?

Question

I’ve not been able to reproduce myself but we’ve noticed from our new relic browser monitoring that lots of errors are being thrown for IE users, and weirdly it’s almost only happening to users in Japan

All of these errors are being thrown from the same place:

And the stack trace is pointing to this return statement in the systemjs library:

For context: we’re importing systemjs into our application like so:

import 'systemjs/dist/system';
import 'systemjs/dist/extras/named-register';

and we’re using window.System.import to asynchronously load javascript

I’ve tried using a VM with windows + IE and changing the language to Japanese but still no luck reproducing.

I just wanted to reach out here in case anyone else has run into anything similar before or if you might have any ideas for what’s going on?

[guybedford]

@billy-reilly as Joel suggests, it sounds like there might be some weird global object difference here.

Can you try replacing that line with the following code:

    return !Obejct.hasOwnProperty.call(global, p)

and let us know if you are still seeing the errors then? If so we can PR this in, but I’d want to be sure it’s the right approach first as well.

[guybedford]

@billy-reilly there is actually a further debugging step that can be taken here, and that is to improve the diagnostic to include the property being checked and to add this property to an opt-out list:

function shouldSkipProperty (p) {
  var hasProperty;
  try {
    hasProperty = global.hasOwnProperty(p);
  }
  catch (e) {
    throw new Error('Error checking property ' + p);
  }
  return !hasProperty || !isNaN(p) && p < global.length || isIE11 && global[p] && typeof window !== 'undefined' && global[p].parent === window;
}

It would be nice to know that it is working on all versions of IE11 so I’ll leave this open in case someone else wants to try. For now SystemJS will be maintaining IE11 support, but will drop it in due course as well I’m sure at which point we could close this too.