Adding segment group functionality to analytics npm package. See the docs https://getanalytics.io/plugins/segment/#adding-group-functionality

extend-segment-plugin.js

import Analytics from 'analytics'
import segmentPlugin from '@analytics/segment'

const originalSegmentInstance = segmentPlugin({
   writeKey: '123-xyz'
})

// Extend originalSegmentInstance with custom methods
const enchancedSegmentInstance = Object.assign({}, originalSegmentInstance, {
  methods: {
    // add analytics.group method https://segment.com/docs/connections/sources/catalog/libraries/website/javascript/#group
    group(groupId, traits = {}, options = {}, callback) {
      const analyticsInstance = this.instance
      
      // If no segment, return early
      if (typeof window.analytics === 'undefined') {
        return
      }
      
      // Make group call to segment
      window.analytics.group(groupId, traits, options, callback)
    },
  }
}

// Initialize analytics instance with plugins
const analytics = Analytics({
  app: 'your-app-name',
  plugins: [
    enchancedSegmentInstance,
  ]
})

// Usage:
// Now you can call segment.group in your app like so
analytics.plugins.segment.group('one', 'two', 'three')