js点击弹出提示层2秒钟之后自动消失

ajax 或者get 请求 发送后 成功给个提示 不想跳转

直接上代码:

<button id="btn" onclick="tan()">btn</button>

function tan(e) {
        var layer=document.createElement("div");
        layer.innerHTML=e
        layer.id="layer";
        var style=
        {
            background:"#ccc",
            position:"absolute",
            zIndex:10,
            width:"200px",
            height:"50px",
            left:"50%",
            bottom:"5%",
            color:"white",
            "text-align":"center",
            "font-size":20,
            "padding-top":"20px"
        }
        for(var i in style)
            layer.style[i]=style[i];
        if(document.getElementById("layer")==null)
        {
            document.body.appendChild(layer);
            setTimeout("document.body.removeChild(layer)",2000)
        }
    }