javascript - Avoid that script in MasterPage and in Iframe child page is executed twice -

i have developed script jquery everytime <select> selection changed logic executed.

initially added script masterpage, in order sure every page considered - however, have external pages (aspx) not use masterpage and, consequence, don't have script.

to solve added same script custom control, rendered <select> , present in external pages. unfortunately in way script executed twice, instead of once.

how can change code in order ensure script executed in every page, once?

user .net's clientscriptmanager.registerclientscriptinclude, has key parameter, register each key once. in masterpage , user control, make sure register them using same key.

you use jquery see if registered , add id:

function requireonce(url) {         if (!$("script[scr='" + url + "']").length) {         $('head').append("<script type='text/javascript' src='" + url + "'></script>");      } } 

above taken here