找出字符串“Can you can a can as a Canner can can a can”中找出所有c的个数，不区分大小写。

实现代码如下：

在线测试
<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <script>
        var str = "Can you can a can as a Canner can can a can";
        var n = 0;
        for(var i=0;i<str.length;i++)
        {
            var char = str.charAt(i);
            //将每一个字符转换为小写，然后判断是否与“c”相等
            if (char.toLowerCase() == "c") {
                n += 1;
            }
        }
        document.write("字符串中含有" + n + "个字母c");
    </script>
</head>
<body>
</body>
</html>

浏览器预览效果如图所示。