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JavaScript Academy · Lesson

The Constraint Validation API

Use built-in validity checking.

Built-in Validation

HTML form fields support attributes like required, min, max, pattern, and type="email". The Constraint Validation API lets JavaScript inspect and control this built-in validation.

checkValidity

checkValidity returns a boolean and fires an invalid event on each failing control without showing the browser’s bubble.

const email = document.querySelector("#email");
console.log(email.checkValidity());

All lessons in this course

  1. Reading Input Values
  2. The submit Event
  3. Client-Side Validation
  4. The Constraint Validation API
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