Why can not he read the property?
objetoSelecionado = document.selectForm.variosDias;
<form name="selectForm">
<select name="variosDias" multiple>
<option value="Domingo">Domingo</option>
<option value="Segunda">Segunda-feira</option>
<option value="Terça">Terça-feira</option>
<option value="Quarta">Quarta-feira</option>
<option value="Quinta">Quinta-feira</option>
<option value="Sexta">Sexta-feira</option>
<option value="Sábado">Sábado</option>
</select>
<input type="button" value="Enviar" onclick="">
</form>
The error appears:
Uncaught TypeError: Can not read property 'severalDays' of undefined