ValidityState: rangeUnderflow property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨July 2015⁩.

The read-onlyrangeUnderflow property of theValidityState interface indicates if the value of an<input>, after having been edited by the user, does not conform to the constraints set by the element'smin attribute.

If the field is numeric in nature, including thedate,month,week,time,datetime-local,number andrange types and amin value is set, if the value doesn't conform to the constraints set by themin value, therangeUnderflow property will be true.

Value

A boolean that istrue if theValidityState does not conform to the constraints.

Examples

Input with numeric underflow

The following example checks the validity of anumeric input element.A constraint has been added using themin attribute which sets a minimum value of18 for the input.If the user enters a number lower than 18, the element fails constraint validation, and the styles matching:invalid and:out-of-range CSS pseudo-classes

css

/* or :invalid */input:out-of-range {  outline: red solid 3px;}

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

html

<pre>Validation logged here...</pre><input type="number" min="18" />

const userInput = document.getElementById("age");const logElement = document.getElementById("log");function log(text) {  logElement.innerText = text;}userInput.addEventListener("input", () => {  userInput.reportValidity();  if (userInput.validity.rangeUnderflow) {    log("Number is too low!");  } else {    log("Valid…");  }});