Q279: What are the DOM methods available for constraint validation - JavaScript Internals (521 Qs)

The below DOM methods are available for constraint validation on an invalid input,

checkValidity(): It returns true if an input element contains valid data.
setCustomValidity(): It is used to set the validationMessage property of an input element. Let's take an user login form with DOM validations

javascript

  function myFunction() {
    var userName = document.getElementById("uname");
    if (!userName.checkValidity()) {
      document.getElementById("message").innerHTML =
        userName.validationMessage;
    } else {
      document.getElementById("message").innerHTML =
        "Entered a valid username";
    }
  }