update-stream

Creates a transform stream that updates/appends records in a stream from a Map based on a version and key field.

const update = require('update-stream');

myObjectStream.pipe(update({
  keyField: 'id', // required
  versionField: '_v', // defaults to 'version'
  changes: new Map() // required, must be a Map
}));

Changes that have a newer version than an existing record will be kept; changes that have an older version than an exising record will be skipped, and changes that had no corresponding existing record will be appended to the stream.