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There was a requirement of deleting multiple options from a listbox using JavaScript. User can select multiple items from a Listbox. Once the delete button is pressed, remove all the values that are selected from the combobox. Now the most intuitive solution for this problem would be to iterate through each option from the listbox and delete it if it is selected. So one would write following piece of HTML & JavaScript.

The HTML

Define a simple listbox with id lsbox and two buttons, Delete & Reset.

<table>
<tr>
 <td align="center">
  <select id="lsbox" name="lsbox" size="10" multiple>
   <option value="1">India</option>
   <option value="2">United States</option>
   <option value="3">China</option>
   <option value="4">Italy</option>
   <option value="5">Germany</option>
   <option value="6">Canada</option>
   <option value="7">France</option>
   <option value="8">United Kingdom</option>
  </select>
 </td>
</tr>
<tr>
 <td align="center">
  <button onclick="listbox_remove('lsbox');">Delete</button>
  <button onclick="window.location.reload();">Reset</button>
 </td>
</tr>
</table>
Code language: HTML, XML (xml)

Below is the JavaScript code.

The (Incorrect) JavaScript

function listbox_remove(sourceID) {

    //get the listbox object from id.
    var src = document.getElementById(sourceID);
 
    //iterate through each option of the listbox
    for(var count = 0; count < src.options.length; count--) {
         //if the option is selected, delete the option
        if(src.options[count].selected == true) {
 
                try {
                         src.remove(count, null);
                        
                 } catch(error) {
                        
                         src.remove(count);
                }
        }
    }
}
Code language: JavaScript (javascript)

That’s it right? Wait, this wont work correctly. Each time you delete an option using src.remove() method, the remaining option’s index will decrease by 1. So if you have selected multiple values to delete, this wont behave as you expected. Check out the below demo:

Demo: The Incorrect Way

In following demo, we used the normal approach (above javascript) to remove the options. 

 So we know the problem now. Each time the value is deleted, the index of option is decremented. So the ideal approach must be to iterate through the options of listbox in opposite way. Thus we start with the last options and iterate till first.

The Correct JavaScript

Notice the loop highlighted line. We are iterating in opposite direction.

function listbox_remove(sourceID) {

    //get the listbox object from id.
    var src = document.getElementById(sourceID);
 
    //iterate through each option of the listbox
    for(var count= src.options.length-1; count >= 0; count--) {

         //if the option is selected, delete the option
        if(src.options[count].selected == true) {
 
                try {
                         src.remove(count, null);
                        
                 } catch(error) {
                        
                         src.remove(count);
                }
        }
    }
}
Code language: JavaScript (javascript)

Following is the demo with correct JavaScript.

Demo: The Correct Way

In following demo, we used the correct approach (javascript) to remove the values. 

 Hope this helps!

Download Source Code

Delete_Multiple_Values_Listbox.zip (1.2 KB)

Update: JQuery Version

It seems that the above code in JavaScript can be replaced with a single JQuery syntax to remove selected items from a listbox. Thanks Ali for the code snippet. Below is the JQuery code for same:

$("#sourceId").find('option:selected').remove();
Code language: JavaScript (javascript)