I know there's a lot of good questions on the site about these two script libraries.
I wanted to ask something that I can't seem to find in any of them though.
What does Modernizr provide that html5shiv doesn't out of the box, that is, just including the script.
I know html5shiv "just" fixes HTML5 elements for IE < 9, does it's support stop there?
Does Modernizr fix CSS3 issues on IE navigators? Does ie9.js do that? (and I mean this particular question out of the box, without additional js code to handle corner-cases)
What are the advantages of Modernizr over html5shiv when you take into account using the library besides just including the script?
They do different things.
Modernizr detects the availability of features in a page allowing you to provide your own polyfills for older browsers should you require that functionality. You can add support for <canvas> using a canvas tag polyfill so that canvas functionality, including it's JavaScript interface, in browsers that don't support the <canvas> tag.
Html5shiv adds the new html5 tags that aren't available (<section>, <header>, etc) to older browsers. It also creates the default styles (display: block for <section> for example).
That's it. It provides no other functionality.