js 获取字符串长度

// 获取字符串长度（汉字算两个字符，字母数字算一个）

        function getBytelength(val) {

            var length = 0;

            for (var i = 0; i < val.length; i++) {

                var a = val.charAt(i);

                if (a.match(/[^\x00-\xff]/ig) != null) {

                    length += 2;

                }

                else {

                    length += 1;

                }

            }

            return length;

        }