multiMap_example.js

const _ = require( 'lodash' )

let aliases = [
  "alias",
  [
    "  aliases    ",
    [
      "idk",
      "TEST ",
      123
    ],
    {
      "a": 12
    }
  ],
  false,
  null,
  null,
  true,
  [
    "IDK",
    function(){},
    zomg => false
  ]
]

const _aliases = _.chain( aliases )
  .thru( _.castArray )
  .flattenDeep()
  .map( val => _.isString( val ) ? val : null )
  .map( _.trim )
  .map( _.toLower )
  .compact()
  .sortedUniq()
  .value()

// Result: ["alias", "aliases", "idk", "test", "idk"]


// _.map() needs to be executed three times to execute 3 functions..
const _aliases = _.chain( aliases )
  .thru( _.castArray )
  .flattenDeep()
  .map( val => _.isString( val ) ? val : null )
  .map( _.trim )
  .map( _.toLower )
  .compact()
  .sortedUniq()
  .value()

// Or a single map, with a lot more functionality
const _aliases = _.chain( aliases )
  .thru( _.castArray )
  .flattenDeep()
  .map( val => _.chain( val )
    .map(val => _.isString( val ) ? val : null )
    .trim()
    .toLower()
    .value() )
  .compact()
  .sortedUniq()
  .value()


// Something like a _.multiMap() would be much easier, like so:
const _aliases = _.chain( aliases )
  .thru( _.castArray )
  .flattenDeep()
  .multiMap( 
    val => _.isString( val ) ? val : null, 
    _.trim, 
    _.toLower 
  )
  .compact()
  .sortedUniq()
  .value()

// Or an array of functions to map
const _aliases = _.chain( aliases )
  .thru( _.castArray )
  .flattenDeep()
  .multiMap([
    val => _.isString( val ) ? val : null, 
    _.trim, 
    _.toLower 
  ])
  .compact()
  .sortedUniq()
  .value()