js判断浏览器的环境（pc端，移动端，还是微信浏览器）

 // 判断浏览器函数
  function isMobile(){
    if(window.navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i)) {
      return true; // 移动端
    }else{
      return false; // PC端
    }
  }

var os = function() { 
   var ua = navigator.userAgent, 
   isWindowsPhone = /(?:Windows Phone)/.test(ua), 
   isSymbian = /(?:SymbianOS)/.test(ua) || isWindowsPhone,  
   isAndroid = /(?:Android)/.test(ua),  
   isFireFox = /(?:Firefox)/.test(ua),  
   isChrome = /(?:Chrome|CriOS)/.test(ua), 
   isTablet = /(?:iPad|PlayBook)/.test(ua) || (isAndroid && !/(?:Mobile)/.test(ua)) || (isFireFox && /(?:Tablet)/.test(ua)), 
   isPhone = /(?:iPhone)/.test(ua) && !isTablet, 
   isPc = !isPhone && !isAndroid && !isSymbian; 
   return { 
     isTablet: isTablet, 
     isPhone: isPhone, 
     isAndroid : isAndroid, 
     isPc : isPc 
   }; 
}(); 
 
// 使用方法 
if(os.isAndroid || os.isPhone){
alert("-----");
}

 var isWechart = function () {
    var rst = true
    if(window.navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i)){
      var ua = navigator.userAgent.toLowerCase();
      if (!(ua.match(/MicroMessenger/i) == "micromessenger")) {
        rst = false;
      }
    }else {
      rst = false;
    }
    return rst;
  }

 //平台、设备和操作系统  
     var system = { 
       win: false, 
       mac: false, 
       xll: false, 
       ipad: false 
     }; 
     //检测平台  
     var p = navigator.platform; 
     system.win = p.indexOf("Win") == 0; 
     system.mac = p.indexOf("Mac") == 0; 
     system.x11 = (p == "X11") || (p.indexOf("Linux") == 0); 
     system.ipad = (navigator.userAgent.match(/iPad/i) != null) ? true : false; 
     //跳转语句，如果是手机访问就自动跳转到wap.baidu.com页面  
     if (system.win || system.mac || system.xll || system.ipad) { 
       alert("在PC端上打开的");
     } else { 
       var ua = navigator.userAgent.toLowerCase();  
       if(ua.match(/MicroMessenger/i)=="micromessenger") {  
         alert("在手机端微信上打开的"); 
       } else {  
         alert("在手机上非微信上打开的"); 
       }  
     }