A jQuery plugin to create a listbox that works as you want
Check out the feature demo on GitLab Pages.
The documentation contains a manual and the source code is documented as well. Access the manual from GitLab Pages or directly.
The following command is used to generate the minified version:
uglifyjs --compress --mangle -- js/jqListbox.plugin-1.3.js > js/jqListbox.plugin-1.3.min.js