How to check if value is not `blank` in this code using Java Script or jQuery?

How to check if value is not `blank` in this code using Java Script or
jQuery?

How to check if value is not blank in this code using Java Script or jQuery?
<select name="producttype" class="selectOption">
<option class="selectOption" value="blank">Select something</option>
<option class="selectOption" value="test1">Test1</option>
<option class="selectOption" value="test2">Test2</option>
<option class="selectOption" value="test3">Test3</option>
</select>