UploadFileToList.js

<!--
  1. The best Idea is that the File Even when Updating other items, 
    will be overwritten, so no need to worry about the update code.
    
    :)
-->
SP.SOD.executeFunc('sp.js', 'SP.ClientContext', function(){

    //your code goes here...
    <div id="message"></div>

    <input type="file" id="uploadInputCSOM" />
    <button id="upload">Upload</button>


    <script
      src="https://code.jquery.com/jquery-2.2.4.min.js"
      integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44="
      crossorigin="anonymous"></script>

    <script language="javascript" type="text/javascript">
    var fileInput;
    $(document).ready(function()   
    {  
        //fileInput = $("#uploadInputCSOM");  
        //SP.SOD.executeFunc('sp.js', 'SP.ClientContext', registerClick);


        $('#upload').click(function (e) {
             e.preventDefault();
             uploadDocument();
        });


        function uploadDocument() {  
            if(!window.FileReader){
                alert("HTM5 File API not Support in this Browser");
                return;
            }

            var context = SP.ClientContext.get_current();
            var web = context.get_web();
            var list = web.get_lists().getByTitle("FilesStore");

            var element = document.getElementById('uploadInputCSOM');
            var file = element.files[0];
            var parts = element.value.split("\\");
            var fileName = parts[parts.length - 1];

            var reader = new FileReader();
            reader.onload = function (e) {
               success1(e.target.result, fileName); 
            }
            reader.error = function (e) {
               success1(e.target.error); 
            }
            reader.readAsArrayBuffer(file);


            function success1(buffer, fileName) {
                // our filebuffer must be 64bit encoded
                var bytes = new Uint8Array(buffer);
                var content = new SP.Base64EncodedByteArray();
                for(var b = 0; b < bytes.length; b++){
                    content.append(bytes[b]);
                }

                var fci = new SP.FileCreationInformation();
                fci.set_content(content);
                fci.set_overwrite(true);
                fci.set_url(fileName);
                var file = list.get_rootFolder().get_files().add(fci);

                var item = file.get_listItemAllFields();
                //item.set_item("Year", new Date().getFullYear());
                item.set_item("Ref_ID", "Ref_4567");
                item.set_item("Employee", web.get_currentUser());
                item.update();

                context.executeQueryAsync(success2, fail);
            }//success1

            function success2() {
                var message = jQuery("#message");
                message.text("Document uploaded");
            }

            function fail(sender, args) {
               alert(args.get_message());
            }
        } // uploadDocument
    });

});
    
</script>