Nodejs - redefining `require` on the client (but not on server) for code-sharing

Redefining nodejs' require on the client, but not on server for code-sharing

I want to share a piece of coffeescript code between the server and the client on Express. I linked the file from the server directory into the /public directory, so it can be loaded by the client. It does have external dependencies, which I resolve statically for the client. To remove the error messages when the client tries to call require, I thought a simple conditional declaration would do.

console.log require
unless require?
  require = (what) ->
    console.info "this is the client, you asked me to load #{what}"
    return {}

However, when run on the server, undefined will be printed and require will be overridden. The same happens for embedded Javascript:

`if( typeof require == "undefined" )
  var require = function(what) {
    console.info( "this is the client, you asked me to load "+what );
    return {};
  }
`

If I only run:

console.log require

on the server, it prints an object structure, as expected. It seems that require is injected after at least the conditional has been evaluated and executed.

How can I override require safely, or what other paradigm might I use for sharing code between client and server?