what is the best option to debug JavaScript function?

[ucu13]

i have a webpage where i use php and javascript function.
it's about map display(mapguid e). i whant to find what is the first function that run??

[Dormilich]

that which is called first in the respective source code.

[ucu13]

it's a very long code..it's not soo eazy..i start this webpage from another page.and depends what link i use..
i have 9926 line of code in this file

[Dormilich]

look for the first occurrence of ); or )