<!DOCTYPE html>
<meta charset="utf-8">
<title>This is the form that will be submitted</title>

<form action="form-echo.py" method="post" enctype="text/plain">
  <input id="input1" type="text">
  <select id="input2">
    <option selected>option
  </select>
  <input id="input3" type="radio" checked>
  <input id="input4" type="checkbox" checked>
</form>

<script>
"use strict";

const form = document.querySelector("form");

for (let el of Array.from(form.querySelectorAll("input"))) { // Firefox/Edge support
  e