optional-require

NodeJS Require that let you handle module not found error without try/catch

optional

Allows you to optionally include modules without surrounding everything with 'try/catch'

browserify-optional

A browserify transform that allows optional dependencies in try..catch blocks

optional-js

Optionals for JS - wrapper for possibly undefined values, inspired by Java Optional API

require_optional

Allows you declare optionalPeerDependencies that can be satisfied by the top level module but ignored if they are not.