分配目标和源中交集的键值的最快方法 object

Question

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?

Answer 1

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)

Answer 2

I think the fastest way is:

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