React: Use the date of birth input as a minimum for the date of death

Since a person can’t die before he/she is born it makes sense to have a min and max for these dates. But I can’t get the value from the 1st input, I get an error that the value is null. (Using the react-hooks-form package, don’t think this information is important but you never know)

<div className="form-section">
            <label>Date of birth <span style={{ color: "red " }}>*</span>:</label>
            {errors.Name && errors.Name.type === "required" && (
              <span style={{ color: "red " }}>Required!</span>
            )}
            <input
              max={moment().format("YYYY-MM-DD")}
              type="date"
              name="BirthDate"
              id="BD"
              ref={register({ required: true })}
            />
          </div>

          <div className="form-section">
            <label>Date of death <span style={{ color: "red " }}>*</span>:</label>
            {errors.Name && errors.Name.type === "required" && (
              <span style={{ color: "red " }}>Required!</span>
            )}
            <input
              min={document.getElementById("BD").value}
              max={moment().format("YYYY-MM-DD")}
              type="date"
              name="DateOfDeath"
              ref={register({ required: true })}
            />
          </div>

Thanks for the help! I can add extra information if needed.

Answer

As the code in questions contains incomplete structure I’m formatting here as per my understanding. If you can provide a working example on codesandbox then it will be a great help.

You need to use watch from react-hook-form.

const MyComponent = () => {
  const {
    register,
    errors,
    watch,
  } = useForm();
  
  const dateOfBirth = watch('BirthDate', new Date()); // Added new date to default to Today in case if DOB is not selected.
  
  return (
    <div className="form-section">
      <label>Date of birth <span style={{ color: "red " }}>*</span>:</label>
      {errors.Name && errors.Name.type === "required" && (
        <span style={{ color: "red " }}>Required!</span>
      )}
      <input
        max={moment().format("YYYY-MM-DD")}
        type="date"
        name="BirthDate"
        id="BD"
        ref={register({ required: true })}
      />
    </div>

    <div className="form-section">
      <label>Date of death <span style={{ color: "red " }}>*</span>:</label>
      {errors.Name && errors.Name.type === "required" && (
        <span style={{ color: "red " }}>Required!</span>
      )}
      <input
        min={dateOfBirth}
        max={moment().format("YYYY-MM-DD")}
        type="date"
        name="DateOfDeath"
        ref={register({ required: true })}
      />
    </div>)
}