HTMLInputElement: checkValidity() method - Web APIs | MDN (original) (raw)

Baseline

Widely available

The checkValidity() method of the HTMLInputElement interface returns a boolean value which indicates if the element meets any constraint validation rules applied to it. If false, the method also fires an invalid event on the element. Because there's no default browser behavior for checkValidity(), canceling this invalid event has no effect.

Syntax

Parameters

None.

Return value

Returns true if the element's value has no validity problems; otherwise, returns false.

Examples

HTML

We include a form containing a required number field and two buttons: one to check the form and the other to submit it.

<form action="#" method="post">
  <p>
    <label for="age">Your (21 to 65) </label>
    <input type="number" name="age" required id="age" min="21" max="65" />
  </p>
  <p>
    <button type="submit">Submit</button>
    <button type="button" id="check">checkValidity()</button>
  </p>
  <p id="log"></p>
</form>

JavaScript

const output = document.querySelector("#log");
const checkButton = document.querySelector("#check");
const ageInput = document.querySelector("#age");

ageInput.addEventListener("invalid", () => {
  console.log("Invalid event fired.");
});

checkButton.addEventListener("click", () => {
  const checkVal = ageInput.checkValidity();
  output.innerHTML = `checkValidity returned: ${checkVal}`;
});

Results

When false, if the value is missing, below 21, above 65, or otherwise invalid, the invalid event will be logged to the console. To report the error to the user, use HTMLInputElement.reportValidity() instead.

Specifications

Browser compatibility

See also