#2628 - JSON Deep Equal

Problem Description

Given two values o1 and o2, return a boolean value indicating whether two values, o1 and o2, are deeply equal.

For two values to be deeply equal, the following conditions must be met:

If both values are primitive types, they are deeply equal if they pass the === equality check.
If both values are arrays, they are deeply equal if they have the same elements in the same order, and each element is also deeply equal according to these conditions.
If both values are objects, they are deeply equal if they have the same keys, and the associated values for each key are also deeply equal according to these conditions.

You may assume both values are the output of JSON.parse. In other words, they are valid JSON.

Please solve it without using lodash's _.isEqual() function

Solution

/**
 * @param {null|boolean|number|string|Array|Object} o1
 * @param {null|boolean|number|string|Array|Object} o2
 * @return {boolean}
 */
var areDeeplyEqual = function(o1, o2) {
  if (o1 === o2) return true;
  if (o1 == null || o2 == null) return false;
  if (typeof o1 !== 'object' || typeof o2 !== 'object') return false;

  if (Array.isArray(o1) !== Array.isArray(o2)) return false;

  if (Array.isArray(o1)) {
    if (o1.length !== o2.length) return false;
    return o1.every((item, index) => areDeeplyEqual(item, o2[index]));
  }

  const keys1 = Object.keys(o1);
  const keys2 = Object.keys(o2);
  if (keys1.length !== keys2.length) return false;

  return keys1.every(key => keys2.includes(key) && areDeeplyEqual(o1[key], o2[key]));
};