Compile regex rule in Node.js?

V8 compiles regexes automatically. See http://www.scribd.com/doc/16921039/V8-Internals-Building-a-High-Performance-JavaScript-Engine

Node.js is just JavaScript running on V8 so you really only have what V8 provides, namely:

var r = new RegExp("abc", 'i');

V8 will do it's own optimization, probably even on inline regexes.