something qs.stringify with indice style for UrlSearchParams

params.js

function appendObject(params, obj, prefix) {
    for (let key of Object.keys(obj)) {
        if (typeof obj[key] === "object") {
            appendObject(params, obj[key], prefix ? `${prefix}[${key}]` : key);
        } else {
            params.append(prefix ? `${prefix}[${key}]` : key, obj[key]);
        }
    }

    return params;
}

let params = new URLSearchParams();

params = appendObject(params, {invoice, invoicePosSave});