ValidityState: valueMissing property

{{APIRef("HTML DOM")}} 

The read-only valueMissing property of the ValidityState interface indicates if a required control, such as an {{HTMLElement("input")}} , {{HTMLElement("select")}} , or {{HTMLElement("textarea")}} , has an empty value.

If the required attribute is set, and no {{HTMLElement("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 {{cssxref(":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);
  }
});

{{EmbedLiveSample("missing_required_input_value", "100%", "140")}} 

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• ValidityState badInput, valid properties.
• Constraint validation
• Forms: Data form validation
• Regular Expressions