The validity read-only property of the HTMLTextAreaElement interface returns a ValidityState object that represents the validity states this element is in.
A ValidityState object.
The following example gets the validity state of a text area element and processes it if it is not valid:
const textArea = document.getElementById("myTextArea");
const validityState = textArea.validity;
if (!validityState.valid) {
// Test each validity state
}