1 module.exports = isFunction
3 var toString = Object.prototype.toString
5 function isFunction (fn) {
6 var string = toString.call(fn)
7 return string === '[object Function]' ||
8 (typeof fn === 'function' && string !== '[object RegExp]') ||
9 (typeof window !== 'undefined' &&
11 (fn === window.setTimeout ||
12 fn === window.alert ||
13 fn === window.confirm ||
14 fn === window.prompt))