Question

I have a select element that shows multiple options with the same text:

 <select name="tur" id="tur">
        <option value="1">a</option> 
        <option value="2">a</option>  
        <option value="3">a</option> 
        <option value="4">a</option>
        <option value="5">b</option> 
        <option value="6">b</option>  
        <option value="7">c</option> 
         <option value="8">d</option>          
          </select>  

Using JavaScript, I would like to remove these duplicates so that only one of each is shown:

<select name="tur" id="tur">
        <option value="1">a</option> 
        <option value="5">b</option> 
        <option value="7">c</option>
        <option value="8">d</option>          

Answer 1

var remove = [], values = {}, value, i;
var options = document.getElementById('tur').getElementsByTagName('option');
for (i=0; i<options.length; i++) {
  value = options[i].innerHTML.replace(/^\s*|\s*$/g, '');
  if (value in values) remove.push(options[i]);
  else values[value] = true;
}

for (i=0; i<remove.length; i++) {
  remove[i].parentNode.removeChild(remove[i]);
}