rangeUnderflow

Summary

Returns whether a value is less than the min attribute on an input control.

Property of dom/ValidityStatedom/ValidityState

Syntax

Note: This property is read-only.

var rangeUnderflow = element.validity.rangeUnderflow;

Return Value

Returns an object of type BooleanBoolean

Whether a value is less than the min attribute.

Examples

The following example validates a numeric (type="number") input field on the onblur event handler. If a number outside the range values of the input control is entered the custom validity message is displayed when the form is submitted.

<label>Enter a number between 4 and 20<br/>
<input id="myField" type="number" required  min="4" max="20" step="2" /></label>
<script type="text/javascript">
var el=document.getElementById('myField');
function validRange(evt){
var el=evt.target;
if(el.validity){
// HTML5 aware browsers
if(el.validity.rangeUnderflow){
el.setCustomValidity('The entered number is outside the acceptable range.');
}else{
el.setCustomValidity("");
}
}else{
// legacy validation

}
}
el.addEventListener('blur',validRange,false);
</script>

Related specifications

W3C HTML5

Working Draft

WHATWG HTML

Living Standard

Attributions

• Microsoft Developer Network: [rangeUnderflow Property Article]

• Portions of this content come from HTML5Rocks! [Making forms fabulous article]