lodash/lang/isFunction.js

define(['../internal/baseIsFunction', '../internal/getNative', '../internal/root'], function(baseIsFunction, getNative, root) {

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

  /** 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;

  /** Native method references. */
  var Uint8Array = getNative(root, 'Uint8Array');

  /**
   * Checks if `value` is classified as a `Function` object.
   *
   * @static
   * @memberOf _
   * @category Lang
   * @param {*} value The value to check.
   * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
   * @example
   *
   * _.isFunction(_);
   * // => true
   *
   * _.isFunction(/abc/);
   * // => false
   */
  var isFunction = !(baseIsFunction(/x/) || (Uint8Array && !baseIsFunction(Uint8Array))) ? baseIsFunction : function(value) {
    // The use of `Object#toString` avoids issues with the `typeof` operator
    // in older versions of Chrome and Safari which return 'function' for regexes
    // and Safari 8 equivalents which return 'object' for typed array constructors.
    return objToString.call(value) == funcTag;
  };

  return isFunction;
});