JavaScript list box listbox full and unselected implementation method

This article illustrates the implementation of the JavaScript listbox listbox full and unselected. Share with you for your reference. The specific analysis is as follows:

Selecting all and unselecting list boxes through the JS code is a frequent and very useful operation.

function listboxSelectDeselect(listID, isSelect) {
  var listbox = document.getElementById(listID);
  for(var count=0; count < listbox.options.length; count++) {
      listbox.options[count].selected = isSelect;
  }
}

Here is an example of how to use it in detail

Click below buttons to select or deselect all options from select box
<br>
  <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> <br>
<button onclick="listboxSelectDeselect('lsbox', true);">Select All</button>
<button onclick="listboxSelectDeselect('lsbox', false);">Deselect All</button>
<script>
function listboxSelectDeselect(listID, isSelect) {
  var listbox = document.getElementById(listID);
  for(var count=0; count < listbox.options.length; count++) {
      listbox.options[count].selected = isSelect;
  }
}
</script>

I hope this article is helpful for you to design javascript program.