How to get the height in textarea in javascript

$('textarea').scrollTop()+$('textarea').innerHeight()

var area= document.getElementById('area');
var contentHeight=area.scrollHeight;

alert('The content height is'+contentHeight+'px.');

if(confirm('Do you want to adjust the element height?)')) {
  area.style.height=contentHeight+'px';
}

<textareaid="area" style="width:250px;height:100px;overflow-y:scroll;">
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</textarea>