.mui-switch:before{
  font-size: 13px;
  position: absolute;
  top: 3px;
  right: 11px;
  content: attr(data-off);
  text-transform: uppercase;
  color: #999;
  }
  .mui-switch.mui-active:before{
  right: auto;
  left: 15px;
  content: attr(data-on);
  color: #fff;
  }



<div class="mui-content">
<ul class="mui-table-view">
<li class="mui-table-view-cell">
<span>报警消息设置</span>
<div class="mui-switch mui-active" id="mySwitch" data-off="关" data-on = "开">
<div class="mui-switch-handle"></div>
</div>
</li> 
</ul> 
</div>

document.getElementById("mySwitch").addEventListener("toggle",function(event){ 
if(event.detail.isActive){
  var btnArray = ['取消', '确认'];
mui.confirm('关闭报警推送消息后,系统将不再推送报警消息"你关闭了报警推送");
}else{
mui("#mySwitch").switch().toggle(); 
}
},'div') 
}else{
  
}
})