The oninvalid
property of the GlobalEventHandlers
mixin is an event handler that processes invalid
events.
The invalid
event fires when a submittable element has been checked and doesn't satisfy its constraints. The validity of submittable elements is checked before submitting their owner form, or after the checkValidity()
method of the element or its owner form is called.
target.oninvalid = functionRef;
var functionRef = target.oninvalid;
functionRef
is a function name or a function expression. The function receives a Event
object as its sole argument.
This example demonstrates oninvalid
and onsubmit
event handlers on a form.
<form id="form">
<p id="error" hidden>Please fill out all fields.</p>
<label for="city">City</label>
<input type="text" id="city" required>
<button type="submit">Submit</button>
</form>
<p id="thanks" hidden>Your data has been received. Thanks!</p>
const form = document.getElementById('form');
const error = document.getElementById('error');
const city = document.getElementById('city');
const thanks = document.getElementById('thanks');
city.oninvalid = invalid;
form.onsubmit = submit;
function invalid(event) {
error.removeAttribute('hidden');
}
function submit(event) {
form.setAttribute('hidden', '');
thanks.removeAttribute('hidden');
event.preventDefault();
}