is.js

/**
 * Returns the internal class name of the given object.
 * @private
 * @param {*} value
 * @param {String} [compare]
 * @returns {Boolean|String}
 */
function _is(value, compare)
{
  var type = Object.prototype.toString.call(value);

  // Extract the real data type e.g. "[object Object]"
  // -----------------------------------------^^^^^^
  type = type.substring(8, type.length - 1);

  return (typeof compare == 'string')
      ? (compare.split(/[^$\w]/).indexOf(type) > -1)
      : type;
}