JSFiddle - React, Tailwind, and code Playground

HTML

<input type="file" id="InputFile">
<button onclick="buttonSubmitClicked(event)">Submit</button>

<script>
function buttonSubmitClicked(event) {
    
        if (!document.getElementById("InputFile").value) {
            event.preventDefault();
            alert("Please choose a file!");
        } else {
            alert("File've been chosen")
        }
    }
</script>