HTMLSelectElement.checkValidity()
  The HTMLSelectElement.checkValidity() method checks
  whether the element has any constraints and whether it satisfies them. If the element
  fails its constraints, the browser fires a cancelable invalid event at the
  element, and then returns false.
Syntax
var result = selectElt.checkValidity();
Specifications
| Specification | 
|---|
| HTML Standard # dom-cva-checkvalidity-dev | 
Browser compatibility
BCD tables only load in the browser