Я думаю, это должно выглядеть так, если я понимаю, что вы имеете в виду
<form action="">
Username: <input type="text" name="usrname">
Password: <input type="password" name="Password">
<input type="submit">
</form>
<p><strong>Note:</strong> The required attribute of the input tag is not
supported in Internet Explorer 9 and earlier versions.</p>
<script>
// append the listeners
document.forms[0].addEventListener('submit', function(evt){
if([
checkName(this.querySelector('[name="usrname"')),
checkName(this.querySelector('[name="Password"'))
].some((v)=>v)) {
evt.preventDefault()
}
})
// check is empty, then notify
function checkName(element){
// if you just have to check if is empty, this is enough
if(element.value) {
return
}
notify(element)
return true
}
// print the message
function notify(element) {
if(element.nextElementSibling.classList.contains('notify')) {
return;
}
element.parentNode.insertBefore(
Object.assign(document.createElement('p'),
{
className: 'notify',
innerHTML: 'Please fill out this field for all empty and required fields'
}
), element.nextSibling)
}
</script>