Optional Object Chaining

A recursive check to test whether a property and any number of sub-keys are an object (similar to optional chaining).

• ES6 function
• ES5 function

Examples:

const colors = {
  orange: true,
  blue: false,
  red: {
    dark: true,
    light: false,
    seeAlso: ['pink'],
  },
};

isObject(colors) // true
isObject(colors, 'orange') // false
isObject(colors, 'red') // true
isObject(colors, 'red', 'dark') // false
isObject(colors, 'red', 'seeAlso') // true