From MozillaZine Knowledge Base
Find As You Type (or Type Ahead Find as it was originally called) allows you to start finding text on the page immediately by simply typing the text you’re trying to find. Normally you need to trigger this feature by pressing ' (single quote) to search link text, or / (forward slash) to search all text. In Firefox, Find As You Type will also display the Find Bar at the bottom of the window and populate the Find field as you type.
Possible values and their effects
Enable Find As You Type.
Disable Find As You Type. (Default in Firefox.)
Tools → Options → Advanced → General / Accessibility → "Search for text when I start typing" (Firefox 2 and above)
Edit → Preferences → Advanced → Keyboard Navigation / Find as You Type → "Find automatically when typing within a web page"
First checked in
2002-08-19 by Aaron Leventhal (checked in as a default feature rather than packaged as an extension)
Has an effect in