Conditionally load and then reference external JS

One possible solution I used

swiperJS.addEventListener('load', callback);

to get the call back

<head>
    <script>
        function loadScript(url, callback) {
            const viewWidth = window.innerWidth;
            if (viewWidth >= 480) {
                console.log('big screen');
                const swiperJS = document.createElement('script');
                swiperJS.type = "text/javascript";
                swiperJS.src = url;
                swiperJS.addEventListener('load', callback);
                document.head.appendChild(swiperJS);
            }
        }

        function init() {
            console.log("inside init")
            const swiper = new Swiper('.swiper');
        }
        loadScript("https://cdnjs.cloudflare.com/ajax/libs/Swiper/7.2.0/swiper-bundle.min.js", init)
    </script>

</head>

<body>
</body>