added isFunction util

Author: Salakar

lib/utils/index.js

@@ -21,6 +21,15 @@ export function isObject(item) {
   return (item && typeof item === 'object' && !Array.isArray(item) && item !== null);
 }
 
+/**
+ * Simple is function check
+ * @param item
+ * @returns {*|boolean}
+ */
+export function isFunction(item) {
+  return (item && typeof item === 'function');
+}
+
 // noinspection Eslint
 export const windowOrGlobal = (typeof self === 'object' && self.self === self && self) || (typeof global === 'object' && global.global === global && global) || this;