Test that Node is a function before using instanceof on it

[evanc]

We use React on a page that also uses the Sarissa library (as part of RichFaces). This library defines its own Node object if the browser doesn't already have one (as IE8 does not). This causes the instanceof check in isNode.js to throw an error.

Reduced test: http://coonrod.org/react/react-0.9.0/examples/basic/

This is the "basic" example from React using the unmodified React 0.9.0. I've added the Sarissa library as well as es5-shim.js and es5-sham.js. If you view it in IE8 you will see something like this:

and the timer does not time.

I believe you want to always use instanceof with a function anyway so it seems like a good thing to test when you don't know if you have a good Node or not.

[vjeux]

cc @yungsters

[syranide]

Seeing as it can only be instanceof Node if it also is a function, this seems like a good fix regardless.

[zpao]

Seems reasonable. Though it also sounds like Sarissa should polyfill Node slightly more correctly (maybe throw or warn intentionally when used as a function). Have you filed a bug with them?

[evanc]

unfortunately it’s not been updated in years, we’re moving away from it but we aren’t able to switch everything all at once.

[zpao]

Thanks Evan!