CODE EXAMPLE FOR JAVASCRIPT

select react hook form yup validation

import React from "react";
import ReactDOM from "react-dom";
import { useForm } from "react-hook-form";
import { yupResolver } from "@hookform/resolvers/yup";
import * as yup from "yup";

import "./styles.css";

const SignupSchema = yup.object().shape({
  select: yup.string().required()
});

function App() {
  const {
    register,
    setValue,
    handleSubmit,
    formState: { errors }
  } = useForm({
    mode: "onChange",
    resolver: yupResolver(SignupSchema)
  });
  const onSubmit = (data) => {
    alert(JSON.stringify(data));
  };

  const doSomething = async (value) => {
    // do something with my select value onChange
  };

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <div>
        <label>Select</label>
        <select
          {...register("select")}
          onChange={(e) => setValue('select', e.target.value, { shouldValidate: true })} // Using setValue
        >
          <option value="">Null</option>
          <option value="1">1</option>
          <option value="2">2</option>
        </select>
        {errors.select && <p>{errors.select.message}</p>}
      </div>
      <input type="submit" />
    </form>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);