From this issue:

The browser example in the readme assumes you are using rollup or webpack. We should write it explicitly.

Both bson.browser.esm.js and bson.browser.umd.js are not standalone files. Which is confusing since most JavaScript that have a dist folder have standalone files there.

The error means that Buffer and Long is undefined

The solution in this case is to use bson.bundle.js. We should document this