PHP does not show search country bar when used to lib intl-tel-input

I’m using lib intl-tel-input version 18.2.1 for my PHP project. I saw at lib doc, it have searching country bar when user click to flag. but in my project. search bar can not display.

<script src="https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/18.2.1/js/intlTelInput.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/18.2.1/js/utils.js"></script>
<script>
    var input = document.querySelector("#phone");
    var iti = window.intlTelInput(input, {
        separateDialCode: false,
        countrySearch: true,
        utilsScript: "https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/18.2.1/js/utils.js"
    });
</script>

this is my code
Thanks for your help