lodash/isNative.js

define(['./isFunction', './_isHostObject', './isObjectLike'], function(isFunction, isHostObject, isObjectLike) {

  /** Used to match `RegExp` [syntax characters](http://ecma-international.org/ecma-262/6.0/#sec-patterns). */
  var reRegExpChar = /[\\^$.*+?()[\]{}|]/g;

  /** Used to detect host constructors (Safari). */
  var reIsHostCtor = /^\[object .+?Constructor\]$/;

  /** Used for built-in method references. */
  var objectProto = Object.prototype;

  /** Used to resolve the decompiled source of functions. */
  var funcToString = Function.prototype.toString;

  /** Used to check objects for own properties. */
  var hasOwnProperty = objectProto.hasOwnProperty;

  /** Used to detect if a method is native. */
  var reIsNative = RegExp('^' +
    funcToString.call(hasOwnProperty).replace(reRegExpChar, '\\$&')
    .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?') + '$'
  );

  /**
   * Checks if `value` is a native function.
   *
   * @static
   * @memberOf _
   * @since 3.0.0
   * @category Lang
   * @param {*} value The value to check.
   * @returns {boolean} Returns `true` if `value` is a native function,
   *  else `false`.
   * @example
   *
   * _.isNative(Array.prototype.push);
   * // => true
   *
   * _.isNative(_);
   * // => false
   */
  function isNative(value) {
    if (value == null) {
      return false;
    }
    if (isFunction(value)) {
      return reIsNative.test(funcToString.call(value));
    }
    return isObjectLike(value) &&
      (isHostObject(value) ? reIsNative : reIsHostCtor).test(value);
  }

  return isNative;
});