src/var/isFunction.js

define( function() {
	"use strict";

	return function isFunction( obj ) {

		// Support: Chrome <=57, Firefox <=52
		// In some browsers, typeof returns "function" for HTML <object> elements
		// (i.e., `typeof document.createElement( "object" ) === "function"`).
		// We don't want to classify *any* DOM node as a function.
		// Support: QtWeb <=3.8.5, WebKit <=534.34, wkhtmltopdf tool <=0.12.5
		// Plus for old WebKit, typeof returns "function" for HTML collections
		// (e.g., `typeof document.getElementsByTagName("div") === "function"`). (gh-4756)
		return typeof obj === "function" && typeof obj.nodeType !== "number" &&
			typeof obj.item !== "function";
	};

} );