JSFiddle - React, Tailwind, and code Playground

by Eugeny Venegrad

HTML

<form method="post" id="form6" name="form6" action="javascript:void(0);" onsubmit="validateForm()">
<textarea name="maintext" id="maintext" rows="6"></textarea><br>
<input name="name" id="nname" type="text"><br>
<input name="email" id="mail" type="text"><br>
<input name="tel6" id="tel6" type="text"><br>
<button type="submit">Задать вопрос</button><br>
</form>

JavaScript

function validateForm() {
  var x1 = document.forms["form6"]["maintext"].value;
  var x2 = document.forms["form6"]["nname"].value;
  var x3 = document.forms["form6"]["mail"].value;
  var x4 = document.forms["form6"]["tel6"].value;
 
  if (x1 == "" || x2 == "" || x3 == "" || x4 == "") {
     alert("Вы заполнили не все поля");
     return false;
  } else { 
     alert("Все хорошо.");
  }
}