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(Reverse('abcde'));
            document.write("<br />");
            </script>
    </body>
</html>