quickest way to assign values of keys which are intersection in the target and source object

user_9709114 0
Viewed 49

I want to assign only those keys which are already present in the target object and not the other keys that are done by the object.assign method.

example
a = { x: 2}
b = {x:3, y:4}

then result = {x:3}

I know there are other ways in past but is there any newer and better ways to do this like in one line?

react-redux assign ecmascript-6 object javascript
2 Answers

You can reduce the keys of the target object to a new object by taking the values from the obj if they exist:

const fn = (target, obj) => Object.keys(target)
  .reduce((acc, key) => key in obj 
    ? { ...acc, [key]: obj[key] } 
    : acc
  , {})

const a = { x: 2}
const b = { x:3, y:4 }

const result = fn(a, b)

console.log(result)

user_51574540

I think the fastest way is:

for (let key in b) {
  if (a[key] === undefined) {
    delete b[key];
  }
}
user_141091630
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