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;
 }