If you are a user of the OS X Text Substitution / Replacement system, you may have noticed it is not supported by Firefox (and perhaps various other applications, although here I’ll focus on Firefox).
The main text substitution I use a lot in a browser is when I am writing a post or comment, etc., and I need an em dash (—). Like the one I just put there in those brackets. Throughout much of OS X I just type two hyphens consecutively (- – [without the space]) and it is automagically replaced by an em dash (—). But not in Firefox. I achieved this in the rest of OS X by using the Text replacement options in the System Preferences > Keyboard > Text options.
Save buying a using a third-part text replacement application (of which there are many) here is the best solution I found for getting my em dashes into Firefox forms and data entry fields, etc.
Fast access to special characters
In the Edit menu, at the bottom you’ll see an option for Special Characters…, and the default keyboard shortcut is ^⌘ Space. This gives fast access to the system-wide special characters map, and especially to any characters you made have favorited in the special characters map. I have, needless to say, favorited the em-dash.
Changing the shortcut assignment for menu option
In my case, I already have ^⌘ Space dedicated to another function. So I needed to change this keyboard shortcut. In case that applies to you, here’s how to do that. Go into the System Preferences and bring up the Keyboard preferences panel. The following image provides the steps to then take. At step 6 you will need to select a keyboard combination that is not otherwise in use either in Firefox or system-wide.
aText and TextExpander
If you have aText or TextExpander (or a similar text replacement application) installed, you can set up your double-dash (–) to em-dash (—) replacement in there. This will work in Firefox.