Question

What I want to do is check if a drop down has one value or none and then make it read only?

if(){
 $('#dropdown').attr("disabled", "disabled");
}


<select class="dropdown" name="dropdown" id="dropdown">
        <option value="L6.5">L6.5</option>
   </select> 

<select class="dropdown" name="dropdown2" id="dropdown2"></select>


<select class="dropinput" name="dropdown3" id="dropdown3">
       <option value=""></option>
       <option value=""></option>
</select>

I need all top three dropdowns to be disabled

Answer 1

According to HTML specs, the select tag in HTML doesn’t have a readonly attribute, only a disabled attribute. Try this it will check for one or no option and disable it accordingly.

var $dd = $('#dropdown');
if($dd.find('option').length <= 1){
    $dd.prop('disabled', true);    
}
else{
    $dd.prop('disabled', false); 
}

Demo