Sets or gets an element's value.
Changing a dropdown's value in code does not trigger an onChange event.
If an element is connected to a dataset, setting the element's value in code does not set the value of the connected field in the dataset. That means if you use the dataset to perform a submit, the value changed in code is not reflected in the submitted item.
To submit the new value using a dataset, set the field's value using the setFieldValue() function before performing the submit.