js alert(“”）弹框 自定义样式

#msg{ 
    height: 2rem; 
    text-align: center; 
    position: fixed; 
    top: 50%; 
    margin-top: -1rem; 
    line-height: 2rem; 
    width: 100%; 
} 
#msg span{ 
    color: #fff; 
    background: rgba(0,0,0,0.6); 
    height: 2rem; 
    display: inline-block; 
    padding: 0 3rem; 
    border-radius: 5px; 
}

function alert(e){ 
    $("body").append("<div id='msg'><span>"+e+"</span></div>"); 
    clearmsg(); 
} 
function clearmsg(){ 
    var t = setTimeout(function(){ 
        $("#msg").remove(); 
    },2000) 
};