Select Tools | Quick Preferences ... from the main menu.
Make sure "Enable JavaScript" is checked.
Opera 6 and 7
Select File | Preferences... from the main menu.
Click Moltimedia.
Under the "JavaScript" heading, select "Enable JavaScript."
Mozilla Seamonkey
Open the Edit menu.
Select Preferences, to open the Preferences dialog box.
In the Category list, click the triangle next to Advanced so that it points downwards.
In the list of items beneath Advanced, click Scripts & Plugins.
To the right of the list, beneath Enable JavaScript for, click Navigator so that a tick appears. (Click again to remove the tick if you want to disable JavaScript.)
Konqueror
Select Configure Konqueror from the Settings menu.
Make sure "Enable JavaScript globally" is checked under the Java & Javascript tab.
Netscape
Select Edit | Preferences… menu item from the main menu.
Click on the Advanced label displayed in the list of options on the left hand side of the Preferences window that pops up.
On the right hand side select the checkbox marked Enable Javascript for Navigator.