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web api instance property

ValidityState: valueMissing property

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The read-only valueMissing property of the ValidityState interface indicates if a required control, such as an <input>, <select>, or <textarea>, has an empty value.

If the required attribute is set, and no <option> is selected or a <textarea> or user-editable <input> is empty, the valueMissing property will be true. The property is only true if the field is required and has no value; if the field is not required, or if the field is required and has a value, the value is false.

Value

A boolean that is true if the ValidityState is not set and the required attribute is.

Missing required input value

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

input:invalid {
  outline: red 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 if (userInput.validity.valueMissing) {
    log("Required field cannot be empty.");
  } else {
    log(`Bad input detected: ${userInput.validationMessage}`);
  }
});
Interactive exampleOpen the canonical MDN source to run this embedded demo.

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.

See also