var countriesArray = $.map(countries, function (value, key) { return { value: value, data: key }; });

// Setup jQuery ajax mock:
$.mockjax({
    url: '*',
    responseTime: 2000,
    response: function (settings) {
        var query = settings.data.query,
            queryLowerCase = query.toLowerCase(),
            re = new RegExp('\\\\b' + $.Autocomplete.utils.escapeRegExChars(queryLowerCase), 'gi'),
            suggestions = $.grep(countriesArray, function (country) {
                 // return country.value.toLowerCase().indexOf(queryLowerCase) === 0;
                return re.test(country.value);
            }),
            response = {
                query: query,
                suggestions: suggestions
            };

        this.responseText = JSON.stringify(response);
    }
});

$('#country').autocomplete({
    lookup: countriesArray,
    minChars: 1,
    onSelect: function (suggestion) {
        $('#selection-country').html('You selected:' + suggestion.value);
    },
    showNoSuggestionNotice: true,
    noSuggestionNotice: 'Sorry,no matching results',
    groupBy: 'category'
});