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javascripthtmlgetboundingclientrect

JavaScript: Position DIV Centered Above Text Selection?

I am trying to position a <div> above a users text selection that will act as a toolbar similar to Mediums.

enter image description here

While I have successfully gotten the <div> to be positioned next to the selection, I cannot seem to get it to correctly center relative to the selection:

    $(function() {
      // Setup the Event Listener
      $('.article').on('mouseup', function() {
        // Selection Related Variables
        let selection = window.getSelection(),
        getRange      = selection.getRangeAt(0),
        selectionRect = getRange.getBoundingClientRect();

        // Set the Toolbar Position
        $('.toolbar').css({
          top: selectionRect.top - 42 + 'px',
          left: selectionRect.left + 'px'
        });
      });
    });

I can determine the selection's center point by subtracting the selections left offset from the viewport by its width as such:

 selectionRect.left - selectionRect.width

However, I am not sure how to use that to set the position of my toolbar to be centered relative to the selection rectangle?

I tried subtracting the toolbars left offset from the width of the selection divided by 2 but that doesn't align to the center perfectly either.

JSFiddle

https://jsfiddle.net/e64jLd0o/

Solution

  • One solution would be to add the following to your CSS:

    .toolbar {
  transform: translateX(-50%);
}

    and update your script to offset the left position of the toolbar element like so:

    $('.toolbar').css({
  top: selectionRect.top - 42 + 'px',
  left: ( selectionRect.left + (selectionRect.width * 0.5)) + 'px'
});

    Here is a working snippet:

    $(function() {
  // Setup the Event Listener
  $('.article').on('mouseup', function() {
    // Selection Related Variables
    let selection = window.getSelection(),
    getRange      = selection.getRangeAt(0),
    selectionRect = getRange.getBoundingClientRect();
     

    // Set the Toolbar Position
    $('.toolbar').css({
      top: selectionRect.top - 42 + 'px',
      left: ( selectionRect.left + (selectionRect.width * 0.5)) + 'px'
    });
  });
});
    .article {
  position: relative;
  height: 300px;
  padding: 20px;
}

.toolbar {
  position: absolute;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 169px;
  padding-top: 10px;
  padding-bottom: 10px;
  background: black;
  text-align: center;
  color: white;
  border-radius: 8px;
  
  transform: translateX(-50%);
}
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0/jquery.min.js"></script>
<!-- Editor -->
<div class="article">
  <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit. Tenetur dignissimos facilis id repellat sint deserunt voluptates animi eaque tempore debitis, perferendis repudiandae voluptatem. Eligendi fuga deleniti saepe quod eum voluptas.</p>
</div>

<!-- Toolbar -->
<div class="toolbar">Toolbar</div>