Rette / debugge javascript i asp .net C#

Hejsa
Hvordan kan jeg debugge javascript i Asp .net C#.

I Internet Explorer får jeg fejlen:

Linje 306
Tegn: 88
Fejl: Strengkonstanten er uafsluttet
Kode: 0

Laver jeg "Vis kilde" ligger der følgende:
Linje 306:
                <td title="MenuID: 156"><table class="MainMenuItemCssClass" id="ctl00_ExtranetMenu1_MenuMaini40" cellpadding="0" cellspacing="0" border="0" width="100%" onmouseover="if (document.readyState == 'complete') aspnm_updateCell('over', 'ctl00_ExtranetMenu1_MenuMaini40', 'MainMenuItemCssClassOver', null, null, 'ctl00_ExtranetMenu1_MenuMain_icon_10');if (document.readyState == 'complete') aspnm_itemMsOver('ctl00_ExtranetMenu1_MenuMaini40', 'ctl00_ExtranetMenu1_MenuMaing41', 'rightdown', 0, 0, 0, null);" onmouseout="if (document.readyState == 'complete') aspnm_updateCell('out', 'ctl00_ExtranetMenu1_MenuMaini40', 'MainMenuItemCssClass', null, null, 'ctl00_ExtranetMenu1_MenuMain_icon_10', '../../Images/SubMenuArrow.gif', null, null, 'MainMenuItemCssClassOver');if (document.readyState == 'complete') aspnm_itemMsOut('ctl00_ExtranetMenu1_MenuMaini40', 'ctl00_ExtranetMenu1_MenuMaing39', 'ctl00_ExtranetMenu1_MenuMaing41', 0, null);" onmousedown="if (document.readyState == 'complete') aspnm_updateCell('down', 'ctl00_ExtranetMenu1_MenuMaini40', 'MainMenuItemCssClassDown', null, null, 'ctl00_ExtranetMenu1_MenuMain_icon_10');" onmouseup="if (document.readyState == 'complete') aspnm_updateCell('up', 'ctl00_ExtranetMenu1_MenuMaini40', 'MainMenuItemCssClassOver', null, null, 'ctl00_ExtranetMenu1_MenuMain_icon_10');" onmousemove="return false;" ondblclick="return false;" onclick="aspnm_hideAllGroups();document.location.href='/Intranet\SP-Internt\Arbejdsmiljoe\APV\';">


Tegn 88 på linje 306:
id="ctl00_ExtranetMenu1_MenuMaini40"


Er det noget jeg kan bruge til at fejlfinde og/eller hvordan finder jeg fejlen?