/**
 * Performs a deep equality check on two JavaScript values.
 */
export function isEqual(a: any, b: any): boolean {
  // If the two values are strictly equal, we are good.
  if (a === b) {
    return true;
  }
  // Dates are equivalent if their time values are equal.
  if (a instanceof Date && b instanceof Date) {
    return a.getTime() === b.getTime();
  }
  // If a and b are both objects, we will compare their properties. This will compare arrays as
  // well.
  if (
    a != null &&
    typeof a === 'object' &&
    b != null &&
    typeof b === 'object'
  ) {
    // Compare all of the keys in `a`. If one of the keys has a different value, or that key does
    // not exist in `b` return false immediately.
    for (const key in a) {
      if (Object.prototype.hasOwnProperty.call(a, key)) {
        if (!Object.prototype.hasOwnProperty.call(b, key)) {
          return false;
        }
        if (!isEqual(a[key], b[key])) {
          return false;
        }
      }
    }
    // Look through all the keys in `b`. If `b` has a key that `a` does not, return false.
    for (const key in b) {
      if (
        Object.prototype.hasOwnProperty.call(b, key) &&
        !Object.prototype.hasOwnProperty.call(a, key)
      ) {
        return false;
      }
    }
    // If we made it this far the objects are equal!
    return true;
  }
  // Otherwise the values are not equal.
  return false;
}