Published
By Thomas McGuire
Editor: Julio Franco

Read user comments

Advanced: Scripting

javascript.enabled (Boolean). JavaScript is an open, cross-platform object scripting language (Not to be confused with Sun MicroSystem's Java) and has proven repeatedly to be a security risk with several (now fixed) vulnerabilities attributed to it e.g. firetabbing and code execution via JavaScript. Setting this to false will provide improved security, although you will likely find many webpages that don’t function correctly as a result. Set this to true should you desire support for JavaScript. Note – This is the same as the Enable JavaScript option in the Content tab.

dom.allow_scripts_to_close_windows (Boolean). This option controls which windows can be closed via script. Setting this to true specifies that any window may be closed and isn’t recommended. Entering false specifies that only windows opened by script can be closed via close().

dom.disable_image_src_set (Boolean). This option determines whether JavaScript is allowed to change images. Set this to true to enable this feature and false to disable it (recommended).

dom.disable_open_click_delay (Integer). This option specifies the amount of time, in milliseconds, that must be surpassed before a pop-up window created by JavaScript setInterval() or setTimeout() calls aren’t managed by current pop-up blocker settings. Beneath this threshold existing pop-up blocker settings are applied. By default this is 1000 (1 second).

dom.disable_open_during_load (Boolean). Set this to true to enable Firefox’s built-in pop-up blocker, which disables the loading of much pop-up content on sites – which will mostly be advertisements (it’s worth noting this is not perfect and will also disable many legitimate pop-ups). Should a pop-up be blocked in this way an information bar will appear at the top of the window, from which you can select what action to take. Setting this to false disables the pop-up blocker (Not recommended). Note – This is the same as the Block pop-up windows option in the Options menu, Content tab.

dom.disable_window_flip (Boolean). This option controls whether JavaScript may be used to bring windows into the foreground/background via focus(). Setting this to true disables such actions, which won’t affect new pop-ups from loading in the foreground, though can force existing ones to remain in the background unless switched to manually. Set this to false to allow the script to determine what happens. Note – This is the same as the Raise or lower windows option in Advanced JavaScript Settings.

dom.disable_window_move_resize (Boolean). This option controls whether JavaScript can be used to move &/or resize windows, whereby setting this to false enables scripts to do this. It would perhaps be best to set this to true, allowing only yourself to resize/move windows. Note – This is the same as the Move or resize existing windows option in Advanced JavaScript Settings.

dom.disable_window_open_feature.close (Boolean). Set this to false to enable the use of scripting to hide the close button of windows, true forces the close button to always be displayed (recommended).

dom.disable_window_open_feature.directories (Boolean). Set this to false to enable the use of scripting to hide the bookmarks toolbar, true prevents the bookmarks toolbar from being hidden in this way.

dom.disable_window_open_feature.location (Boolean). Set this to false to enable the use of scripting to hide the Location (Address) bar, true prevents the Address bar from being hidden.

dom.disable_window_open_feature.menubar (Boolean). Set this to false to enable the use of scripting to hide the Menu bar, true disables the hiding of the Menu bar.

dom.disable_window_open_feature.minimizable (Boolean). Set this to false to enable the use of scripting to disable the minimizing of windows, true enables the minimizing of such windows (recommended).

dom.disable_window_open_feature.resizable (Boolean). Set this to true to enable the use of scripting to hide the close button of windows, false forces the close button to always be displayed (recommended).

dom.disable_window_open_feature.scrollbar (Boolean). Set this to false to enable the use of scripting to hide the Scroll bar in windows, true disables the hiding of the Scroll bar in windows.

dom.disable_window_open_feature.status (Boolean). This option controls whether JavaScript can be used to hide the status bar, whereby setting this to false enables scripts to do this. Set this to true to force the status bar to be displayed at all times. Note – This is the same as the Hide the status bar option in Advanced JavaScript Settings.

dom.disable_window_open_feature.titlebar (Boolean). Set this to false to enable the use of scripting to hide the Title bar of windows, true forces the Title bar to always be displayed.

dom.disable_window_open_feature.toolbar (Boolean). Set this to false to enable the use of scripting to hide the Navigation toolbar, i.e. Back, Forward, etc. buttons, false prevents the hiding of the Navigation toolbar.

dom.disable_window_status_change (Boolean). This option controls whether JavaScript can be used to display custom text in the status bar, e.g. moving the mouse over a hyperlink normally would display where the link points to, though a script could be used to display something else instead. Set this to false to allow such custom status bar text displayed, while true will disable this. Note – This is the same as the Change status bar text option in Advanced JavaScript Settings.

dom.event.contextmenu.enabled (Boolean). This option controls whether JavaScript can be used to alter, or even disable the context menu, e.g. right clicking could be disabled on certain pages. Set this to true if you wish to allow sites to be able to do this, while false ensures scripts can’t be used to alter this functionality. Note – This is the same as the Disable or replace context menus option in Advanced JavaScript Settings.

dom.max_script_run_time (Integer). This specifies the amount of time, in seconds, that a script in content may run before being prompted whether to continue running it or not – the default value being 10. It's recommended you leave this at 10 unless you have a specific reason to change it, in which case you can raise the value to allow for a higher number of seconds, or alternatively set 0; which allows scripts to run as long as required (Though I’d doubt most reading this would need to do that). Note – Prior versions of Firefox defaulted to 5 seconds; however this was increased due to popular sites timing out

dom.max_chrome_script_run_time (Integer). This specifies the amount the amount of time, in seconds, that a script with chrome privileges may run before being prompted whether to continue running it or not – the default being 20.

dom.popup_maximum (Integer). This value specifies the maximum number of pop-up windows that may be open simultaneously. By default this is set to 20, which no doubt might seem like an excessive amount. Unless you have a particular reason to allow so many to be open at once, it would be a good idea to lower this value (Considering certain sites out there try flooding you with numerous pop-ups). Personally I’ve set this to 5.