Is es5-sham required for IE8?

[sophiebits]

NormalizedEventListener uses Object.create which is unavailable in IE8 and isn't added by es5-shim. (edit: no longer.)

It is added by es5-sham but the common questions doc on the React site doesn't say that es5-sham is also required. Not sure if this is a docs problem or if there's a good way to avoid Object.create.

(Side note: it's a little bit of a pain to test in IE8 since neither the website nor most of the examples include es5-shim (or es5-sham).)

[zpao]

Turns out that Object.create in NormalizedEventListener is actually causing some bugs, so we just changed that internally. We're still working out the kinks to our code sync process but that should be making it's way to master soon.

In the meantime, if having es5shim+sham on the site would help, we can make that happen.

[sophiebits]

I can't tell from your answer whether that means that es5-sham should be used and its presence can be relied upon, or if it should go away completely once the code sync happens.

Having the shims on the site might help. How have you been testing in IE8? (Also in general – I've been repeatedly running grunt build then using the examples to test but maybe there's some good way of loading React that doesn't require the explicit build step?)

[zpao]

es5-sham might be able to go away (I don't actually know all the polyfills we need and which live in shim vs sham). I know for sure we need something to completely support IE8. Even if we get rid of this Object.create we have some Array.isArray in there. We should document this better.

Our IE8 testing has been facebook.com :) In general though, if you're making internal changes then you'll need to rebuild to test. grunt build builds debug and minified builds - you can skip the minified step by just run grunt build:basic, might make that cycle a little faster. You could also run the automated tests in browser with grunt test --debug which should start a server which you can hit from any browser. This doesn't help the shim issue though, so probably won't be much use in IE8.

Having a no-build way to test would be smart. I bet we could maybe do it using requirejs or maybe a node server that just builds react.js on demand... but for now building is the only option.

[benjamn]

FWIW grunt test builds just enough stuff to run the Jasmine specs, so it takes a lot less time than grunt build.

[sophiebits]

I made a quick attempt to use React with the only the necessary parts of es5-shim and it appears that Function.prototype.bind, Array.isArray, and Array.prototype.indexOf are the only needed functions. I wonder if it's worth including just those ~50 lines of code in React directly and claiming native IE8 support?

edit: Also Date.now(), but that can be replaced with +new Date without hurting anyone.

[steida]

I suppose it's because Array.prototype methods like map or Function.prototype.bind are useful in render method. And IE8 is dying.

[petehunt]

This can be closed now, right @zpao @spicyj ?

[zpao]

Yea, we talk about all the polyfills needed in the "Browser Suppport and Polyfills" (oh man clownshoes) section of http://facebook.github.io/react/docs/working-with-the-browser.html