javascript - Using underscore to filter out a nested object and return an array

Question

const newData = _.pluck(_.flatten(_.values(file)), 'Message')

This is the correct way to return an array with all the messages values from this giant nested object, which is great. However I want to exclude the values which are also set with local = true in the object.

I only want ['LAJDH', 'NPSABA'] returned. Essentially what I am doing is writing tests in jest which will open up thousands of files and return me an array to use. I'm exporting this object to be required in each iteration in my jest test.

This means it would be awesome to have this executed as fast as possihle.

Example data:

{ onOrder: [],
  onGo: [],
  onDelivery:
   [ { Trigger: 'Ready To Dispatch',
       Channel: 'Mail',
       Message: 'AJDSA',
       local: true
       Recipient: [Array],
       Filter: [Array] },
     { Trigger: 'Ready to Delivery',
       Channel: 'Mail',
       Message: 'LAJDH',
       Recipient: [Array],
       Filter: [Array] } ],
  onDelay:
   [ { Trigger: 'Delay',
       Channel: 'Mail',
       Message: 'ABJSH',
       local: true,
       Recipient: [Array],
       Filter: [Array] } ],
  onDelivered:
   [ { Trigger:
       'Delivered',
       Channel: 'Mail',
       Message: 'NPSABA',
       Recipient: [Array],
       Filter: [Array] } ] }

question from:https://stackoverflow.com/questions/65937334/using-underscore-to-filter-out-a-nested-object-and-return-an-array

Answer 1

_.reject is Underscore's negative filter function. All you need to do, is to sandwich it in between _.flatten and _.pluck. Note that this code uses an iteratee shorthand.

const newData = _.pluck(_.reject(_.flatten(_.values(file)), {local: true}), 'Message');

Tip: long expressions like these become more readable with _.chain.

const newData = _.chain(file)
    .values()
    .flatten()
    .reject({local: true})
    .pluck('Message')
    .value();