【display】
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'>
window.onload=function(){
function isHidden(elem) {
return elem.offsetWidth <= 0 && elem.offsetHeight <= 0;
}
foo = document.getElementById("foo")
console.log(isHidden(foo))
}
</script>
</head>
<body>
<div style="display: none">
<div id="foo" style="width: 100px; height: 100px">hi</div>
</div>
</body>
</html>
