countProperties
Given an object, return the total number of properties it has.
Examples
countProperties({a: 1, b: 2, c: 3}) → 3
countProperties({}) → 0
Starter code
function countProperties(obj) {
}
Complexity of the optimal solution
Time O(n), space O(n). `Object.keys(obj)` creates an array containing all 'n' property names of the object. This operation takes O(n) time and O(n) space. Getting the length of the array is then a constant time operation.