only-nested

Return on the whitelisted properties of an object, similar to only, but with support for nested properties.

Installation

$ npm isntall only-nested --save

Usage

var only = require('only-nested')
 
var whitelist = {
  a: null,
  b: {
    x: null,
    y: null
  }
}
 
var obj = {
  a: 1,
  b: {
    x: 2,
    y: 3,
    z: 4
  },
  c: 5
}
 
only(whitelist, obj)
/*
-> {
  a: 1,
  b: {
    x: 2,
    y: 3
  }
}
*/

Arrays of Objects

The only() function also supports whitelisting keys of objects in an array. This is expressed in the whitelist by having an array with a whitelist object as the first element.

var whitelistWithArray = {
  a: [{
    x: null
  }]
}
 
var objWithArray = {
  a: [
    {
      x: 1,
      y: 2
    },
    {
      x: 3,
      y: 4,
      z: 5
    }
  ]
}
 
only(whitelistWithArray, objWithArray)
/*
-> {
  a: [
    {
      x: 1
    },
    {
      x: 3
    }
  ]
}
*/

Partial Application

If you call only() with a whitelist as the only argument, it returns a partially applied function which takes a source object as its only argument.

var onlyWhitelist = only(whitelist)
onlyWhitelist(obj)

It works great with map().

someArrayOfObjects.map(only({a: null}))