I am learning javascript on the fly and would like to know how to set the focus to a specific value in a select box when it is selected.

Here is my code for the select box (in the case, selAMIBetDose is the select box I am displaying) :

if (selectedValue == "AtenololQD") {
document.getElementById('selAMIBetDose').style.display = ""
document.getElementById('selAMIBetDose_1').style.display = "none"
document.getElementById('selAMIBetDose_2').style.display = "none"
document.getElementById('selAMIBetDose_3').style.display = "none"


I would just like to add some type of focus line in this script to get the focus to one of the values in the dropdown.