Отправка файлов ajax

uploadFiles.js

//<input type="file" data-upload-file>
//<input type="file" multiple data-upload-file>
//ловим в файле ajax.php $_FILES['files'] и $_POST['action'] == "uploadFiles"

$(document).on("change", "[data-upload-file]", function(e){
        e.preventDefault();
        const formData = new FormData();
        formData.append("action", "uploadFiles");
        for(let k = 0; k < e.target.files.length; k++) {
            formData.append("files[" + k + "]", e.target.files[k]);
        }
        $.ajax({
            url: "ajax.php",
            data: formData,
            type: "POST",
            cache: false,
            processData: false,
            contentType: false,
            dataType: 'json',
            beforeSend: function () {

            },
            success: function (msg) {
                //console.log(msg);
            }
        });
    })