Constraint Validation DOM Methods
| Property | Description |
|---|---|
| checkValidity() | Returns true if an input element contains valid data. |
| setCustomValidity() | Sets the validationMessage property of an input element. |
If an input field contains invalid data, display a message:
The checkValidity() Method
<input id="id1" type="number" min="100" max="300"
required> <button onclick="myFunction()">OK</button> <p id="demo"></p> <script> function myFunction() {
const inpObj = document.getElementById("id1");
if (!inpObj.checkValidity()) {
document.getElementById("demo").innerHTML = inpObj.validationMessage;
}
}
</script>Constraint Validation DOM Properties
| Property | Description |
|---|---|
| validity | Contains boolean properties related to the validity of an input element. |
| validationMessage | Contains the message a browser will display when the validity is false. |
| willValidate | Indicates if an input element will be validated. |
Validity Properties
The validity property of an input element contains a number of properties related to the validity of data:
| Property | Description |
|---|---|
| customError | Set to true, if a custom validity message is set. |
| patternMismatch | Set to true, if an element's value does not match its pattern attribute. |
| rangeOverflow | Set to true, if an element's value is greater than its max attribute. |
| rangeUnderflow | Set to true, if an element's value is less than its min attribute. |
| stepMismatch | Set to true, if an element's value is invalid per its step attribute. |
| tooLong | Set to true, if an element's value exceeds its maxLength attribute. |
| typeMismatch | Set to true, if an element's value is invalid per its type attribute. |
| valueMissing | Set to true, if an element (with a required attribute) has no value. |
| valid | Set to true, if an element's value is valid. |