Execute a JS/jQuery function on focus

<script>
function disableDays(selector,days,min) {
    var $ = jQuery;
    var daysToDisable = days; // [5, 6] // Sat & Sun

    function disableSpecificWeekDays(date) {
        var day = date.getDay();
        for (i = 0; i < daysToDisable.length; i++) {
            if ($.inArray(day, daysToDisable) != -1) {
                return [false];
            }
        }
        return [true];
    }

    $(selector).datepicker('option', 'beforeShowDay', disableSpecificWeekDays);
    $(selector).datepicker('option', 'minDate', min);
}
</script>

<script>
jQuery('#input_2_75').one('focus',function() {
  disableDays('#input_2_75',[0,6],'+4d')
});
</script>