Function that will find intersecting keys for n number of object arguments.

intersectingKeys.js

export function intersectingKeys(...objects) {
  return objects
    .map((object) => Object.keys(object))
    .sort((a, b) => a.length - b.length)
    .reduce((a, b) => a.filter((key) => b.includes(key)));
}

How do you find intersecting keys of n number of objects?

1. First we build an array where each element is the set of keys of each object.
2. Then we sort the lists of keys from smallest to largest, this is for efficiency
3. Then we reduce the set of keys, by comparing A set of keys to B set of keys, finding the intersecting of keys. Each iteration the previous result is compared to the next set.
4. Finally return the resulting set of intersecting keys