Select an option in select tag by value

<SELECT name="fruit">
  <OPTION value="apple">apple</option>
  <OPTION value="orange">orange</option>
  <OPTION value="pear">pear</option>
</SELECT>

If you need to select an option in a select tag by index you can do the following:

document.getElementById('dropDown').selectedIndex = 1;

But if you want to select an option in a select tag by value you can do the following:

for(var i=0; i<document.getElementById('dropDown').options.length;i++)

        if(document.getElementById('dropDown').options[i].value == "MYVALUE")
          document.getElementById('dropDown').selectedIndex = i;