HTML `dialog` element: scroll content independently of background

Question

I am trying to use the dialog element.

When the dialog/modal is closed, the body should be scrollable.

When the dialog/modal is open, if it has larg

Answer 1

Simple solution is : Once the mnodel is displayed make a one more DIV as overlay which covers full screen, in that place css { pointer-events:none} and model will be placed on top of that. user can not click on body content other than model data.

I have created sample: http://jsfiddle.net/z3sgvnox/

  

    

      

        
          Cancel
        
      
    
  

  
    Open Dialog
  

CSS

#container {
  height: 100vh;
  width: 100vw;
  position: fixed;
  top: 0;
  left: 0;
  background: #ccc;
}

#my-dialog {
  margin-top: 1rem;
  margin-bottom: 3rem;
  width: 50%;
  overflow-y: auto;
      max-height: 80%;
}
.hideScroll{
  overflow:hidden;
  pointer-events:none;
}

#my-dialog__content {
  display: flex;
  flex-direction: column;
  height: 200vh;
}

menu {
  width: 100%;
  padding: 0;
  margin: 0 auto;
}

#cancel-button {
  width: 100%
}

JS:

(function() {
  var openBtn = document.getElementById('open-dialog');
  var myDialog = document.getElementById('my-dialog');
var bodyData = document.getElementById('content-body');
  openBtn.addEventListener('click', function() {
    if (typeof myDialog.showModal === "function") {
      myDialog.showModal();
      bodyData.classList.add("hideScroll");
    } else {
      alert("Dialog API not supported by browser");
    }
  });

})();