How to set the 'selected' (default) value for an HTML <select> element with JavaScript. Aka. currently option0 is 'selected', how to run a script to change it to display the value i want?

this for example because that value is previously saved in a database, and i only want it updated if the user actually specifies to do so. But if i don't specify the value (by re-selecting the previous option), saving the 'edit' will overwrite the previous value with the 'default selected' value the <select> is loaded with.

<select id="selector" name="selector">
  <option id="option0" value="0" selected=true >default </option>
  <option id="option1" value="1">option 1 </option>
  <option id="option1" value="2">option 2 </option>
  <option id="option1" value="3">option 3 </option>
  <option id="option1" value="4">option 4 </option>
</select>

NOTE: Because i lack reputation to add my answer (below) to the general thread on this topic, here the solution i got to using javascript, to set an option to be the option displayed/selected in the selector. This can also be a <%= value %> from a database.