Doesn't work in IE 8.0.7601.17514 / Win 7

I’ve just tried your polyfill in the above version and it doesn’t work. It fails here: https://github.com/eligrey/classList.js/blob/master/classList.js#L174

Turns out the exception thrown isn’t what you were expecting. The exception has no number property. It is a TypeError stating that “getters & setters can not be defined on this javascript engine”.

Removing the condition if (ex.number === -0x7FF5EC54) { ... fixes the problem.

[eligrey]

I’m super busy with my proprietary stuff and missed this a year ago. I merged #43 just now.

I’m sorry about this issue affecting any of you. Please tell me if the changes I have merged have fixed this issue for you.

[david-mark]

What you had hold of initially was an ActiveX exception (the number is an HRESULT). Clearly IE 11 is no longer using ActiveX objects behind the scenes.

Might as well remove the check as it simply causes all other exceptions to fail silently. There’s really no way to deal with the exception anyway. What’s the point of having it enumerable in some browsers and not in others?

Realize this will never be a perfect imitation of classList. It’s simply an impossible task; for one, the array-like object returned is not live. Then there’s the unsolvable IE 8- issue at hand.

A “polyfill” that doesn’t actually work as expected only serves to deceive other scripts. It fools their feature detection into thinking that the feature is there, but it’s really just an incomplete imposter.

In general, DOM “polyfills” are highly ill-advised and this one is a good example of why. Better to write wrappers (e.g. hasClass, addClass, etc.)

Also note that transpiling is just a red herring here.

HTH