Yes. Someone I know needs IE7 in 2019 and wants React. (dramatic lightning; thunder)
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README.md

preact_ie7

Yes. Someone I know needs IE7 in 2019 and wants React. (dramatic lightning; thunder)

image



Come on. No.

Yeah.

So the gag is, my buddy had to do some dev, wanted React, but needed to be able to target MS Office.

Sure, it's 2019. Sure, IE is cancelled. Sure, Edge is Chrome now.

But Office still embeds MSHTML7.2, which is IE7.

And his stuff needed to work inside of Office.

... sooooooo.



Okay so why preact

Because have you ever shimmed React? It punched me in the eye 😢

I tried. Rly I did. For minutes. But also I knew it was utterly doomed, and I was just making sure things hadn't changed. Rolling back React to IE7 even with shims is, like, 0.6 or 0.7 I think? And let's be honest, we're not getting back out of the babel era. Nah.

Then I tried inferno, because it's hipster bullcrap and so am I, which means I love it. However, I couldn't get past certain IE8 topics, so IE7 was out of reach.

Then I tried preact, but I actually couldn't make it work either.

So I tried next and nuxt and nerv. I thought about trying vue but I didn't want to have to beat myself up afterwards, so, that was out. I tried HTM, zeit, hyperscript, mithril, and then I got angry at myself for even knowing the name glimmer.

viper, stencil, dojo 2, mobx, quasar, cxjs, riot, and deku were right up front that this wasn't an option.

cyclejs, elm, amber, angular, canjs, wijmo, w2ui, angulardart, compost, marko widgets, spree, apprun, jsblocks, blocks.js, blok, knockout, ractive, aurelia, sencha ext.js, and w3 components were not considered, as too different.



Is that literally every library on NPM?

no, there's still d3

But anyway after all those went poof I had a sad, and I did what every programmer does.

I decided to point my finger at a library, yell "that one" really loudly at my laptop, then I went to chat and I whined at the author. Turns out he's super generous with his time, and he helped get this banged out in a couple hours.



You're lying. The internet doesn't help

I know, right?

But this repo, combined with a look at my general incompetence, is proof.



Enough schtick. What is this?

This is preact bent just-so to work under IE7.

It's probably rickety.

This is a babel 6 (not 7, old shims) stack run through rollup, which has a bunch of shims in place that make things Work ™.

Problematically, two things have to be extraneously shimmed, and they have to be before anything else. Sooooo, there's a block of code you actually have to copy paste, like a troglodyte. (It's index.js lines 2-55 at the time of this writing.)



But why

Well

In addition to the shims, we need to do one horrible thing and one really horrible thing

This is such a bad idea 😅

The horrible thing is we shim out addEventListener and removeEventListener by checking for their absence on window then assuming that means it's old-IE and putting in some attachEvent half-bakery. This is horrible because attachEvent can't do some of the stuff aEL and rEL do, and other things are going to think that's real.

The really horrible thing we do?

Uuuuuh. The only thing we couldn't shim in IE7 was that preact wants to set a property on TextNodes as a boolean, and IE7 isn't okay with that.

Couldn't find an alternative.

So ... 😅😅😅 we incorrectly shimmed document.createTextNode 😅😅😅

the worst anything ever. really. what happens when anything else uses it?

in prod, this could be scoped within an iframe, but, like. g'lawd

So what it actually does is return a tag node instead of a text node. Which is super wrong and not-compliant.

But also the tag node, which has an illegal name x-text that shouldn't collide, also has the things preact needs.

So that gets it to render. (Somewhat slowly, because preact's VDOM always thinks it's changed. But, for simple stuff, this should be enough.)



Et voilà

(but really this is a bad idea and only to be used under duress)

Many thanks to @developit from preact team for helping me commit this sacreilege.

Try it (on IE7, lol) here.