js实现获取网络类型的方法

   function getNetworkType() {
            var ua = navigator.userAgent;
            var networkStr = ua.match(/NetType\/\w+/) ? ua.match(/NetType\/\w+/)[0] : 'NetType/other';
            networkStr = networkStr.toLowerCase().replace('nettype/', '');
            var networkType;
            switch (networkStr) {
                case 'wifi':
                    networkType = 'wifi';
                    break;
                case '4g':
                    networkType = '4g';
                    break;
                case '3g':
                    networkType = '3g';
                    break;
                case '3gnet':
                    networkType = '3g';
                    break;
                case '2g':
                    networkType = '2g';
                    break;
                default:
                    networkType = 'other';
            }
            return networkType;
        }