How to trigger autocomplete select event in jquery with the first item

Question

Here I am scripting a web scrap in winform using cefsharp. I need to trigger a autocomplete select event whenever an autocomplete open event occurs.

The actual method which was in the web page is

$('.tb').on('autocompleteselect', function (e, ui) {
        console.log(ui.item.value);
});

The ui.item.value is printing on the console exactly. But in the following method

$('.tb').bind( 'autocompleteopen', function(e, ui) {
                $('.HiddenSearchId').val(ui.item.value);
                $('.HiddenSearchBtn').click();
                });

But on that ui.item.value is not getting. How do I get the first suggested ui.item.value from the autocomplete list. Following by I need to trigger a click event. Either I need to get the UI VALUE in autocompleteopen or I need to trigger the autocomplete select with the first element.any help appreciated.