css js show or hide on click

<script type="text/javascript">
<!--
    function toggle_visibility(id) {
       var e = document.getElementById(id);
       if(e.style.display == 'block')
          e.style.display = 'none';
       else
          e.style.display = 'block';
    }
//-->
</script>

<!-- Inline Usage in HTML -->
<a href="#" onclick="toggle_visibility('foo');">Click here to toggle visibility of element #foo</a>
<div id="foo">This is foo</div>function myFunction() {
  var x = document.getElementById("myDIV");

    if (x.style.display 
=== "none") {
    x.style.display = "block";
  } else {
    x.style.display = 
  "none";
  }
}