原生js创建模态框

1.效果图如下：

2.代码如下：

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Test</title>
<style>
#pageMask {
visibility: hidden;    
position: absolute;
left: 0px;    
top: 0px;
width:100%;
height:100%;
text-align: center;
z-index: 1100;
background-color: #333; 
opacity: 0.6;
}
#ModalBody{
background: white;
width: 50% !important;
height: 50% !important;
position:absolute;
left: 25%;
top: 25%;
z-index: 1101;
border: 1px solid;
display: none;
}
#closeModalBtn{
position: static;
margin-top: 5px;
margin-right: 1%;
float: right;
font-size: 14px;
background: #ccc0;
cursor: pointer;
}
</style>
</head>
<body>
<div class="content">
<h1>Test Modal</h1>
<div id="pageMask"></div>     <!--遮盖层-->
<button class="showModalBtn" id="showModalBtn">Btn</button>
<div>    <!--主页面-->
Page Content...
</div>
</div>
<div id="ModalBody">    <!--模态框-->
<button id="closeModalBtn" style="display: none;">Close</button>
<div>Test Modal Body...</div>
</div>
<script>
window.onload = function(){
expandIframe();
}
function expandIframe(){
var mask = document.getElementById("pageMask");
var modal = document.getElementById("ModalBody");
var closeBtn = document.getElementById("closeModalBtn");
var btn = document.getElementById("showModalBtn");
btn.onclick = function(){
modal.style.display = (modal.style.display == "block")? "none" : "block";
closeBtn.style.display = (closeBtn.style.display == "block")? "none" : "block";
mask.style.visibility = (mask.style.visibility == "visible")? "hidden" : "visible";
}
closeBtn.onclick = function(){
modal.style.display = (modal.style.display == "block")? "none" : "block";
closeBtn.style.display = (closeBtn.style.display == "block")? "none" : "block";
mask.style.visibility = (mask.style.visibility == "visible")? "hidden" : "visible";
}
}
</script>
</body>
</html>