I think you're misunderstanding it. JS2-mode is a few years old and a generic javascript mode with a built-in AST and all the goodness that comes from that.
It does not inherently understand require.js. Nor does ST. With Emacs's JS2-mode, thanks to its AST, it is possible to augment the library so that it does understand require.js -- and the author does so without resorting to piles-upon-piles of regexp hacks.
It does not inherently understand require.js. Nor does ST. With Emacs's JS2-mode, thanks to its AST, it is possible to augment the library so that it does understand require.js -- and the author does so without resorting to piles-upon-piles of regexp hacks.