JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <form id="form" action="" method="post">
        <input type="file" id="fileInput" />
         <input type="submit" value="submit form" id="cmdSubmit">        
    </form>
</html>

JavaScript

$(function () {
    $("#cmdSubmit").bind("click", function () {
        var file = document.getElementById("fileInput").files[0];
        alert(file);
        
        file = $("#fileInput").val();
        alert(file);
        
        file = $("#fileInput").files[0];
        alert(file);
        
    });        
});