console 命令行工具 X clear
console
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title></title>
  </head>
  <body>
    <script>
        function Reverse(str)
        {
            var arr =[];
            for(var i=str.length-1;i>=0;i--)
            {
                arr.push(str[i]);
            }
            return arr.join("");
        }
        document.write("颠倒顺序后："+Reverse('abcde'));
    </script>
  </body>
</html>