I'm not saying a rewrite is necessary at all, but refactoring this code to use more modern standards would NOT increase the line count at all, my guess it it might cut it by 15%+ in total size if you leveraged the beautiful builtin functions. Compare these:

    function addClass (el, cl) { if (el) { var a = el.className.split(' '); if (!afind(cl, a)) { a.unshift(cl); el.className = a.join(' ')}} }

Could turn into something like this:

  const addClass = (el, cl) => el.classList.add(cl)

Not only is is shorter, but it's more readable too!

> Not only is is shorter, but it's more readable too!

And won't work on IE. Not just because of el.classList, but also because of the arrow notation. So by doing this change, you either have to ditch one of still used browsers, or introduce a stupidly complex transpilation chain into the mix.

I'm aware, but I'm responding to the myth of:

> Any effort in trying to bring it up to modern webdev standards would likely make the code expand significantly

That's just not true, and nowhere did that person say: "Because of legacy IE support requirements", they only mentioned "modern webdev standards".

Are you suggesting arrow functions, and classList aren't modern standards then?

I was that person, and what I meant was that "modern webdev standards" would include modules and features requiring transpilation, which would introduce many dependencies, all of which count into code size (you have to keep track of them mentally).

Why/where would modules be necessary here? Just because there's a feature now that didn't exist years ago doesn't mean it's the right time & place to use it. The code works as-is, a small refactor to leverage built-in functions to do some of the trickier logic parts would make this code a breeze. There's no need for something like Babel to help out with a small refactor.

el.classList isn't supported by IE < 10

And is it accurate to describe IE < 10 as "more modern"?

It isn't, and I don't think I have.

My point was that using a "more modern standard" would break hn for people using legacy browsers.