JSFiddle - React, Tailwind, and code Playground
HTML
<select multiple="" name="selectinputmultiple" id="">
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
</select>
JavaScript
$('select[name=selectinputmultiple]').on('change', function () {
var val=$('select[name=selectinputmultiple] option:selected').map(function () {
return this.value;
}).get();
console.log(val)
});