lodash/lang/isArguments.js

define(['../internal/isLength', '../internal/isObjectLike'], function(isLength, isObjectLike) {

  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
  var undefined;

  /** `Object#toString` result references. */
  var argsTag = '[object Arguments]';

  /** Used for native method references. */
  var objectProto = Object.prototype;

  /**
   * Used to resolve the [`toStringTag`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.prototype.tostring)
   * of values.
   */
  var objToString = objectProto.toString;

  /**
   * Checks if `value` is classified as an `arguments` object.
   *
   * @static
   * @memberOf _
   * @category Lang
   * @param {*} value The value to check.
   * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
   * @example
   *
   * _.isArguments(function() { return arguments; }());
   * // => true
   *
   * _.isArguments([1, 2, 3]);
   * // => false
   */
  function isArguments(value) {
    var length = isObjectLike(value) ? value.length : undefined;
    return isLength(length) && objToString.call(value) == argsTag;
  }

  return isArguments;
});