How do I make Firefox pop up something on every Javascript error? I don't want to use add-ons for this basic functionality, I don't need fancy debugging or anything, just to immediately see if there's a Javascript error and on which line it is.

I tried about:config and setting devtools.errorconsole.enabled to true, but it still won't report errors (IE and Opera do).

How do I make Firefox pop up something on every Javascript error? I don't want to use add-ons for this basic functionality, I don't need fancy debugging or anything, just to immediately see if there's a Javascript error and on which line it is.

I tried about:config and setting devtools.errorconsole.enabled to true, but it still won't report errors (IE and Opera do).

• javascript
• firefox

3 Answers 3

Firefox uses the error console to present the errors found on a web page.

To see it, press ctrl + shift + j.

Other browsers like Microsoft Internet Explorer have opted to alert the errors found by default, that is why you see them on an popup.

As can be read on the MDN Error Console page:

The Error Console is a tool available in most Mozilla-based applications that is used for reporting errors in the application chrome and in web pages user opens. It reports JavaScript-related errors and warnings, CSS errors and arbitrary messages from chrome code. In Firefox, the Error Console can be opened from the tools menu or by Ctrl-Shift-J.

For an immediately presentation of errors on Firefox, for anyone willing to use add-ons:

Console² has an option to gain focus automatically when errors are found.

Web Developer contains three icons, one for DocType, other for CSS and other for JS errors, allowing you to know whenever an error occurs.

Hit Ctrl-Shift-J and you'll get the error console. That should be all you need, right? You can see every error as it occurs in a separate window, along with its line number.

There is add-on that does exactly what you asked about.

See JavaScript Errors Notifier Add-on for Firefox