I don't get what's happening with that "hello" example...
so for browsers that don't recognize the <article> tag the tag is wrapped in a div... and that's it??
and how do you then style these elements for browsers that don't recognize them?
<font face='Courier New'>var elm = document.createElement("DIV");
elm.innerHTML = "<article> Hello <\\/article>";
seems exceedingly vague... just create a div? and place it where??? and won't this line
<font face='Courier New'>elm.innerHTML = "<article> Hello <\\/article>";</font>
insert <article> elem inside every div on the page?
so this is what you do for every HTML tag a browser doesn't recognize? like <section>?? just wrap it in a div??
and, again, how do you style these elements not recognized by IE??? (or other browsers that don't recognize certain elements, for example <details> is not supported in Android or Windows phones...)
I have used modernizr successfully for placeholders for text fields in forms, but I don't know what to do about HTML5 tags not supported by all browsers..