自定义弹框（手机端），定时消失

//文字弹框，1秒后消失
function txt_layer_glo(txt, time) {
var txt_layer = " <p class="txt_layer" style="position:fixed;z-index:100;left:10%;top:50%;margin-top:-20px; 80%;text-align:center;line-height:40px;background-color:rgba(0,0,0,.7);color:#fff;border-radius:4px;">" + txt + "</p>";
if ($("body .txt_layer").length > 0) {
$(".txt_layer").show();
$(".txt_layer").text(txt);
} else {
$("body").append(txt_layer);
}
setTimeout(function () { $(".txt_layer").hide() }, time);
}