Convert JavaScript object to FormData. Modified from [this answer](https://stackoverflow.com/a/49388446/2530736) on StackOveflow

objectToFormData.js

objectToFormData(obj, rootName, ignoreList) {
    var formData = new FormData();

    function appendFormData(data, root) {
        if (!ignore(root)) {
            root = root || '';
            if (data instanceof File) {
                formData.append(root, data);
            } else if (Array.isArray(data)) {
                for (var i = 0; i < data.length; i++) {
                    appendFormData(data[i], root + '[' + i + ']');
                }
            } else if (typeof data === 'object' && data) {
                for (var key in data) {
                    if (Object.prototype.hasOwnProperty.call(data, key)) {
                        if (root === '') {
                            appendFormData(data[key], key);
                        } else {
                            appendFormData(
                                data[key],
                                root + '[' + key + ']'
                            );
                        }
                    }
                }
            } else {
                if (typeof data !== 'undefined') {
                    formData.append(root, data ?? '');
                }
            }
        }
    }

    function ignore(root) {
        return (
            Array.isArray(ignoreList) &&
            ignoreList.some(function(x) {
                return x === root;
            })
        );
    }

    appendFormData(obj, rootName);

    return formData;
}