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MDN / ValidityState: valid property

The read-only valid property of the ValidityState interface indicates if the value of an <input> element meets all its validation constraints, and is therefore considered to be valid.

If true, the element matches the CSS pseudo-class; otherwise the CSS pseudo-class applies.

Value

A boolean that is true if the ValidityState does conform to all the constraints.

Examples

Displaying validity state

The following example checks the validity of a numeric input element. A constraint has been added using the min attribute which sets a minimum value of 18 for the input. If the user enters any value that’s not a number greater than 17, the element fails constraint validation, and the styles matching input:invalid are applied.

input:invalid {
  outline: red solid 3px;
}
input:valid {
  outline: palegreen solid 3px;
}

body {
  margin: 0.5rem;
}
pre {
  padding: 1rem;
  height: 2rem;
  background-color: lightgrey;
  outline: 1px solid grey;
}

<pre id="log">Validation logged here...</pre>
<input type="number" id="age" min="18" required />

const userInput = document.getElementById("age");
const logElement = document.getElementById("log");

function log(text) {
  logElement.innerText = text;
}

userInput.addEventListener("input", () => {
  userInput.reportValidity();
  if (userInput.validity.valid) {
    log("Input OK…");
  } else {
    log("Bad input detected…");
  }
});

Specifications

Browser compatibility

See also