If you WEREN'T a prototype user (MochiKit here), you had to deal with their Object.prototype extensions. All frameworks at the time had specific checks to handl

If you WEREN'T a prototype user (MochiKit here), you had to deal with their Object.prototype extensions. All frameworks at the time had specific checks to handle the prototype.js extensions because it was the most popular framework and (like jQuery today) people would just add it to your pages. Unlike jQuery, it caused things to blow up in not-immediately-apparent ways.