Fastest way to remove all items from dropdown list or listbox?

Question

I have a dropdown list with more than one thousand items. Once I click on clear button it should clear all items. For removing I tried looping.

What would be the fastest way to remove all items from a dropdown list or listbox?

Answer 1

Set innerHTML of select box as empty string.

var selectBox = document.getElementById("selectboxID");
selectBox.innerHTML = "";

Answer 2

An option if you're using jQuery:

$("#selectboxID").empty();