JSFiddle - React, Tailwind, and code Playground

http://stackoverflow.com/questions/17125242/validation-for-dynamic-control-in-javascript http://www.quirksmode.org/dom/w3c_traversal.html

by lalatino

HTML

<form name="form1" action="" method="post" onsubmit="return validateForm()">
    <input type="text" name="text1" value="text" />
    <button type="submit" id="send"> Send </button>
</form>

JavaScript

window.onload = function(){
    var form = document.forms['form1'];
    var sendButton = document.getElementById('send');
    var elem = document.createElement('input');
    elem.setAttribute('type',"text");
    elem.setAttribute('name',"text2");
    //elem.setAttribute('required',"required");
    form.insertBefore(elem, sendButton);
    //form.onsubmit = validateForm;
}

function validateForm() {
    var form = document.forms['form1'];
    var status = true;
    var message = '';
    if (form.text1.value == '') {
        status = false;
        message += 'Text1 is missing! ';
    }
    if (form.text2.value == '') {
        status = false;
        message += 'Text2 is missing! ';
    }
    if (message != '') {
        alert(message);
    }
    return status;
}