console 命令行工具 X clear
console
<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title></title>
    </head>
    <body>
        <script>
            var str ="Rome was not built in a day";
            arr =str.replace(/\s/g);  //不计算空格 
            var sum =0;
            for(var i of str)
            {
            sum++;
            }
            document.write(sum);
        </script>
    </body>
</html>