Mozilla Firefox. In the address bar at the top, type “about:config” and hit “Enter”. If a window pops up, choose “I’ll be careful, I promise” to the security warning message. Search for “JavaScript.enabled”. Toggle the preference “JavaScript.enabled” (to toggle, right click and select “Toggle” or just double click the preference) in order to change the selection from “false” to “true”. Apple Safari. Select “Edit” on the web browser menu and select “Preferences”. Select the “Security” tab. In the “Web Content” section, mark the “Enable JavaScript” box. To reload the page, click on the “reload the page” button in the browser.