One of the beauties of Firefox 3 is its ability to do spelling check as and when users do the typing. The built-in spell checker application program in the Firefox browser will flag words in a document when users do not spell correctly. It lets users enter text directly into web pages such as blog posts, web-based email, forum, etc without any typos or spelling mistakes. To activate the feature, users just need to go to Tools -> Option -> Advanced -> and check the “Check My Spelling As I Type” box. Even though the built-in spell checker is useful, the setback for it is it doesn’t work in web form. When users enter data or fill out a form, the spelling check doesn’t work in the text fields. To extend this handy feature in web form, there is little users need to do to modify the hidden preference for the spell-checker to work in web form.

Firstly, open the Firefox browser. Type about:config in the location bar and press Enter to display the list of user preferences.
01aboutconfig

Type in “spellcheck” in the Filter box.
02spellcheck

Look for the item “layout.spellcheckDefault”, right click for menu shortcut. Select “Modify” to edit the value.
03modify

Change the value from 1 to 2.
04entervalue

Users need to restart Firefox browser to activate the setting.