Result Size: 625 x 534
x
 
<!DOCTYPE html>
<html>
<head>
<style>
#test {
  left: 100px;
  margin: 10px;
  padding: 10px;
  width: 300px;
  position: relative;
  border: 5px solid black
}
</style>
</head>
<body>
<div id="test">
  <p>单击按钮获取测试 div 的 offsetLeft。</p>
  <p><button onclick="myFunction()">试一试</button></p>
  <p>offsetLeft is: <span id="demo"></span></p>
</div>
<script>
function myFunction() {
  var testDiv = document.getElementById("test");
  document.getElementById("demo").innerHTML = testDiv.offsetLeft;
}
</script>
</body>
</html>