​x
 
<!DOCTYPE html>
<html>
<body>
​
<h1>JavaScript 错误</h1>
​
<p>您不能将数字转换为大写：</p>
​
<p id="demo"></p>
​
<script>
var num = 1;
try {
  num.toUpperCase();
}
catch(err) {
  document.getElementById("demo").innerHTML = err.name;
}
</script>
​
</body>
</html>
​
​