Modifying the built-in behavior of ajax tag type-ahead functionality of WordPress

Question

Currently, it takes 3 characters to be entered into the tags, before WordPress can start suggesting matching tags.

Where do I make it so it instantly starts those suggestions?

I've got a 100's of tags that start with dash character (-) and I'd like to get to them real fast.

in my custom taxonomy, "source", I tag the organization names starting with dash. Example, -cnn, -bbc, -kabc, -new your times etc. and I tag the author names normally such as Larry King. To get to the orgs being suggested fast, I thought I need to modify the at-least-3-letter-needed behavior. This way, I can just type -c and boom -cnn would be showing.

Feel free to comment to this approach please.

Answer 1

Very difficult. The value is hard coded in wp-admin/js/post.js. See wp-admin/js/post.dev.js tagBox.init() for more readable code:

$(this).suggest( ajaxurl + '?action=ajax-tag-search&tax=' + tax, 
{ 
    delay: 500, minchars: 2, multiple: true, multipleSep: postL10n.comma + ' ' 
} );

The only solution I can see: Unregister the script with the handle 'post' (see wp-includes/script-loader.php) and register a custom copy where you change the minchars value.