Set a variable equal to null if it is not included in an array?

Question

If I have something like,

const {
  someProperty,
  anotherProperty,
  thirdProperty
} = someObject;

const includeProperties = ['someProperty', 'thirdProperty']

Is it possible to make anotherProperty = null?

I want to destructure first, and then conditional set a value to null if it doesn't exist in includeProperties — Mike K
– Mike K, Commented Feb 19, 2020 at 11:30
const { someProperty, anotherProperty, thirdProperty } = someObject; By this, you are trying to declare those variables right? — i_sapumal
– i_sapumal, Commented Feb 19, 2020 at 11:35
Have you solved your problem or still looking for some better options? — Yevhen Horbunkov
– Yevhen Horbunkov, Commented Feb 20, 2020 at 13:33

Yevhen Horbunkov · Accepted Answer · 2020-02-19 12:09:08Z

2

You may nullify all the not needed properties within source object shallow copy and destructure that:

const srcObj = {a:1, b:2, c:3},
      neededKeys = ['a','b'],
      objCopy = (obj =>
        (Object.keys(obj).forEach(key =>
          !neededKeys.includes(key) && (obj[key]=null)), obj)
      )({...srcObj}),
      {a,b,c} = objCopy
      
console.log(a,b,c)

.as-console-wrapper{min-height:100%;}

edited Feb 19, 2020 at 12:09

answered Feb 19, 2020 at 11:27

Yevhen Horbunkov

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2 Comments

Mike K Over a year ago

This does not answer the question. Property c in obj would exist in the case of the question.

Yevhen Horbunkov Over a year ago

@MikeK : considering your use case, that would be easier to nullify unwanted props before destructuring

Akshay Bande · Accepted Answer · 2020-02-19 11:30:49Z

1

You can use Array.prototype.reduce

let properties = [
  'someProperty',
  'anotherProperty',
  'thirdProperty'
]

const includeProperties = ['someProperty', 'thirdProperty'];

let object = properties.reduce((acc, val) => {

  if (includeProperties.indexOf(val) === -1) 
    acc[val] = null;
  else 
    acc[val] = 'some value';
  
  return acc;
}, {});

console.log(object);

answered Feb 19, 2020 at 11:30

Akshay Bande

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Comments

i_sapumal · Accepted Answer · 2020-02-19 11:58:28Z

0

    let someProperty = someObject,
       anotherProperty = someObject,
       thirdProperty = someObject;

    const includeProperties = [someProperty, thirdProperty];

if (!includeProperties.include(someVariable))
    someVariable= null;
}

This is a possible way to do what you asked.

edited Feb 19, 2020 at 11:58

answered Feb 19, 2020 at 11:46

i_sapumal

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3 Comments

i_sapumal Over a year ago

Is this what you expected?

Mike K Over a year ago

But this is not dynamic in any way. I might not know the properties to nullify.

i_sapumal Over a year ago

Do you want to nullify the variable if it is not in array?

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