javascript - Undefined media issue -

i maintaine web site of friend of mine, , console logs following error:

get https://www.my-client-site.ext/undefined 404 (not found)       undefined:1 

the problem can't find location of call in page.

i have try search page source code, , cannot find referense url.

also have try check js files break points, , still cannot find issue.

is there other way make reseach particular issue ?

go firefox , install addon called firebug.

https://addons.mozilla.org/en-us/firefox/addon/firebug/

now open firebug , go console tab, firebug show javascript calling ajax in right corner of pane.

hope helps.