Test a few parameter examples.

Edit code and click me	Your Result (Some examples do not work in Google Chrome):
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <script src="http://code.jquery.com/jquery-latest.js"></script> <script> $(document).ready(function(){ function stub() { } var objs = [ function () {}, { x:15, y:20 }, null, stub, "function" ]; jQuery.each(objs, function (i) { var isFunc = jQuery.isFunction(objs[i]); $("span").eq(i).text(isFunc); }); }); </script> <style> div { color:blue; margin:2px; font-size:14px; } span { color:red; } </style> </head> <body> <div>jQuery.isFunction(objs[0]) = <span></span></div> <div>jQuery.isFunction(objs[1]) = <span></span></div> <div>jQuery.isFunction(objs[2]) = <span></span></div> <div>jQuery.isFunction(objs[3]) = <span></span></div> <div>jQuery.isFunction(objs[4]) = <span></span></div> </body> </html>
Edit the code above and click to see the result	www.xhtml.co.il - Try it yourself