deep equals method for comparing variables including objects

tiny-equals.js

/**
 *
 * This will deep check two variables including objects
 * It works in IE9+
 * Note: equals(NaN, NaN) uses js default behaviour: false
 *
 * equals(1, 1) --> true
 * equals(1, 2) --> false
 *
 * equals({a: 1}, {a: 1}) --> true
 * equals({a: 1}, {a: 2}) --> false
 *
 * equals({a: [{b: 2}]}, {a: [{b: 2}]}) --> true
 * equals({a: [{b: 2}]}, {a: [{b: 3}]}) --> false
 *
 * equals(new Date(1), new Date(1)) --> true
 * equals(new Date(1), new Date(2)) --> false
 *
 * @param o1 any value
 * @param o2 any other value to compare to o1
 * @returns {boolean}
 */
function equals(o1, o2) {
  if (o1 === o2) return true;
  if (typeof o1 !== typeof o2 || !!o1 !== !!o2) return false;
  if (Array.isArray(o1) !== Array.isArray(o2)) return false;
  if (Array.isArray(o1)) {
    return o1.length === o2.length && !o1.some(function (o1Item, index) {
        return !equals(o1Item, o2[index])
      });
  } else if (typeof o1 === 'object') {
    if (o1 instanceof Date) return o1.getTime() === o2.getTime();
    var o1Keys = Object.keys(o1);
    var o2Keys = Object.keys(o2);
    return o1Keys.length === o2Keys.length && !o1Keys.some(function (o1Key) {
        return !equals(o1[o1Key], o2[o1Key])
      });
  }
  return false;
}

Thanks, exactly what I need