Untitled

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <div class="form">
        <form id="frm" action="/regulations" method="POST">
            <div id="container">
                <div class="fields">
                    <label>Правило:</label>
                    <input type="text" name="regexp" placeholder="regexp(e.g. ^\+|^\-)">
                    <label>Тип данных:</label>
                    <input type="text" name="type" placeholder="e.g. money">
                </div>
            </div>
            <input type="submit">
        </form>
    </div>
    <button id="add-form">ADD</button>

    <script>
        (function(){
            const btn = document.getElementById("add-form");
            let forms = document.getElementById("frm");

            const listenerCallback = function(e){
                e.preventDefault();
                let regs = document.querySelectorAll('input[name=regexp]');
                let types = document.getElementsByClassName('input[name=type]');
                let rg = [], tp = [];
                for (let reg of regs) {
                    rg.push(reg.value);
                }
                for(let type of types){
                    tp.push(type.value);
                }
                let xhr = new XMLHttpRequest();
                xhr.open('POST', '/regulations', false);
                //тело можно сформировать в разных форматах
                xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');//формат тела запроса (пример https://learn.javascript.ru/xhr-forms)
                //xhr.setRequestHeader('Content-Type', 'application/json');
                let body = 'regexp = ' + encodeURIComponent(rg) + '&type = ' + encodeURIComponent(tp);  //формирование тела запроса (зависит от формата), здесь кодировка - urlencoded
                //let body = JSON.stringify({regexp: rg, type: tp}); //здесь формат JSON
                xhr.onreadystatechange = function(){
                    if(this.status === 200){
                        console.log('получение данных');
                    }else{
                        console.log('error');
                    }
                }
                xhr.send(body);
            }

            forms.onsubmit = e => listenerCallback(e);

            btn.onclick = function(e){
                e.preventDefault();
                addForm("container", createDiv("fields"));
            }

            const createDiv = function(divClass){
                let fields = document.getElementsByClassName(divClass)[0].innerHTML;
                let div = document.createElement('div');
                div.innerHTML = fields;
                div.classList.add(divClass);
                return div;
            }

            const addForm = function(block, div){
                let form = document.getElementById(block);
                form.appendChild(div);
            }
        })()
    </script>
</body>
</html>