Based on Activity Feed’s documentation, Here’s an example list of messages read from an SQS queue:

[
  {
    deleted: [],
    deleted_foreign_ids: [],
    new: [
      {
        actor: '1',
        verb: 'tweet',
        object: '1',
        target: null,
        time: '2014-12-15T17:20:37.258',
        foreign_id: null,
        id: 'af781804-847e-11e4-8080-80012fb97b9e',
        tweet: 'Hello world'
      }
    ],
    published_at: '2014-12-15T17:20:37.263518+00:00',
    feed: 'user:2',
    app_id: '123'
  }
],
[
    {
        deleted: ['38f81366-847f-11e4-9c94-0cc47a024be0'],
        deleted_foreign_ids: [['your_foreign_id', '2014-12-15T17:20:37.263518+00:00']],
        new: [],
        published_at: '2014-12-15T17:20:37.263518+00:00',
        feed: 'timeline:1',
        app_id: '123'
    }
];

How could we find the "verb" of a "delete" item?

There is a "verb" key for each of the "new" items but that is missing in the "deleted" list and I want to access that while updating some activity verb-based counter.
It would be great if you refer to the documentation of javascript SDK.