How to implement “mustMatch” and “selectFirst” in jQuery UI Autocomplete?

I think I solved both features…

To make things easier, I used a common custom selector:

$.expr[':'].textEquals = function (a, i, m) {
    return $(a).text().match("^" + m[3] + "$");
};

The rest of the code:

$(function () {
    $("#tags").autocomplete({
        source: '/get_my_data/',
        change: function (event, ui) {
            //if the value of the textbox does not match a suggestion, clear its value
            if ($(".ui-autocomplete li:textEquals('" + $(this).val() + "')").size() == 0) {
                $(this).val('');
            }
        }
    }).live('keydown', function (e) {
        var keyCode = e.keyCode || e.which;
        //if TAB or RETURN is pressed and the text in the textbox does not match a suggestion, set the value of the textbox to the text of the first suggestion
        if((keyCode == 9 || keyCode == 13) && ($(".ui-autocomplete li:textEquals('" + $(this).val() + "')").size() == 0)) {
            $(this).val($(".ui-autocomplete li:visible:first").text());
        }
    });
});

If any of your autocomplete suggestions contain any ‘special’ characters used by regexp, you must escape those characters within m[3] in the custom selector:

function escape_regexp(text) {
  return text.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
}

and change the custom selector:

$.expr[':'].textEquals = function (a, i, m) {
  return $(a).text().match("^" + escape_regexp(m[3]) + "$");
};