What does a trailing slash in the parameter of require.resolve() mean?

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While setting up a build system with webpack 5.1.1 today webpack informed me that since 4.x the API has changed and webpack no longer includes polyfills for Node.js core modules by default, but that I can include one myself by using require.resolve() to add fallbacks for when these are missing (which they obviously are in non-Node contexts).

So far so good. What was not clear however was why in some of these instructions a trailing slash was put after the name of the module whereas in other cases there was no trailing slash.

Excerpts from the log:

Example without trailing slash:

If you want to include a polyfill, you need to:
    - add a fallback 'resolve.fallback: { "stream": require.resolve("stream-browserify") }'
    - install 'stream-browserify'

Example with trailing slash:

If you want to include a polyfill, you need to:
    - add a fallback 'resolve.fallback: { "buffer": require.resolve("buffer/") }'
    - install 'buffer'

Which brings me to my question: What does a trailing slash in the parameter of require.resolve() mean?

webpack node.js require
1 Answers

The idea is the following. buffer is one of core node modules. If you do require.resolve('buffer') node module resolution algorithm will find this file lib/buffer.js. But you want it to actually bypass core module and lookup in node_modules folder. Adding trailing slash does the trick.

From buffer module docs

To depend on this module explicitly (without browserify), require it like this:

var Buffer = require('buffer/').Buffer // note: the trailing slash is important!

To require this module explicitly, use require('buffer/') which tells the node.js module lookup algorithm (also used by browserify) to use the npm module named buffer instead of the node.js core module named buffer!

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