CODEWITHSUNDEEP
javascriptvue.jsspread-syntax
sluz
sluz

Reputation: 25

Javascript object spread with an object that may have undefined objects as data in its properties

Hey I'm trying to fill out an empty placeholder object (which in this case serves as a v-model for vue, but not important exactly to the case). The object that I'm expanding the original with may or may not have some objects inside it undefined, but i need to keep the structure of the first object no matter the structure of incoming one. For example Object 1

let object1 = { a : '', b : '', c : {name : 'Mark', title: 'Mr'}}

and Object 2 which will sometimes come like this

let object2 = { a : 'AAA', b : 'BBB', c : undefined}

I need to keep the structure of object 1 even if the other object has the property c undefined. In this case

let object1 = { a : 'AAA', b : 'BBB', c : {name : 'Mark', title: 'Mr'}}

Thanks

Upvotes: 0

Views: 505

Answers (2)

Yury Tarabanko
Yury Tarabanko

Reputation: 45121

If you want to use spread syntax you could define a simple helper proxy that filters own keys to those having values other than undefined

let object1 = {a: '', b: '', c: {name: 'Mark', title: 'Mr'}}

let object2 = {a: 'AAA', b: 'BBB', c: undefined}


const result = { ...defined(object1), ...defined(object2) }

console.log(result)

function defined(obj) {
  return new Proxy(obj, {
    ownKeys() {
      return Object.keys(obj).filter(key => obj[key] !== undefined)
    }
  })
}

Upvotes: 0

Boussadjra Brahim
Boussadjra Brahim

Reputation: 1

Try to spread the object2 as first item, then add property c as second :

  object1={...object2,c:object1.c}

or

   object1={...object2,  c : object2.c ? object2.c : object1.c}

Upvotes: 2

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