​x
 
<!DOCTYPE html>
<html>
<head>
<style>
#myDiv {
  border: 1px solid #FF0000;
}
</style>
</head>
<body>
​
<div id="myDiv" style="padding-bottom:5cm;">这是 div。</div>
<br>
<button type="button" onclick="myFunction()">返回下内边距</button>
​
<script>
function myFunction() {
  alert(document.getElementById("myDiv").style.paddingBottom);
}
</script>
​
</body>
</html>
​