Writing modular code using "require"

The espruino command line now supports require() as per node . It implements the logic of node's require().resolve according to the rules set out at https://nodejs.org/dist/latest-v5.x/docs­/api/modules.html#modules_all_together (with the exceptions of not supporting node binaries *.node and only looking in the modules folder in the current working directory, not recursively following back up to the path to the root)

See this post

That includes files, folders, sub-folders, .json, index.js and package.json support.

This hasn't made its way to the WebIDE and I don't know if it ever will.