js判断是否微信浏览器

/*判断（微信）浏览器*/

function isWeiXin(){
var ua = window.navigator.userAgent.toLowerCase();
if(ua.match(/MicroMessenger/i) == ‘micromessenger‘){
return true;
}else{
return false;
}
}

if(isWeiXin()){
alert(1);
}
else{
alert(2);
}