//基本结构
(function(window,document){
var MaskShare = function(){
//代码
};
MaskShare.prototype = {
//代码
};

window.MaskShare = MaskShare;
}(window,document));

//实际封装的遮罩层
(function(window,document){
var MaskShare = function(targetDom,options){
// 判断是用函数创建的还是用new创建的。这样我们就可以通过MaskShare("dom") 或 new MaskShare("dom")来使用这个插件了
if(!(this instanceof MaskShare))return new MaskShare(targetDom,options);

// 参数合并
this.options = this.extend({
// 这个参数以后可能会更改所以暴露出去
imgSrc:"../static/img/coupon-mask_1.png"
},options);

// 判断传进来的是DOM还是字符串
if((typeof targetDom)==="string"){
this.targetDom = document.querySelector(targetDom);
}else{
this.targetDom = targetDom;
}

var boxDom = document.createElement("div");
var imgDom = document.createElement("img");

// 设置默认样式 注意将z-index值设置大一些，防止其他元素层级比遮罩层高
boxDom.style.cssText = "display: none;position: absolute;left: 0;top: 0;width: 100%;height:100%;background-color: rgba(0,0,0,0.8);z-index:9999;";
imgDom.style.cssText = "margin-top:20px;width: 100%;";

// 追加或重设其样式
if(this.options.boxDomStyle){
this.setStyle(boxDom,this.options.boxDomStyle);
}
if(this.options.imgDomStyle){
this.setStyle(imgDom,this.options.imgDomStyle);
}

imgDom.src = this.options.imgSrc;
boxDom.appendChild(imgDom);
this.boxDom = boxDom;

// 初始化
this.init();
};
MaskShare.prototype = {
init:function(){
this.event();
},
extend:function(obj,obj2){
for(var k in obj2){
obj[k] = obj2[k];
}
return obj;
},
setStyle:function(dom,objStyle){
for(var k in objStyle){
dom.style[k] = objStyle[k];
}
},
event:function(){
var _this = this;

this.targetDom.addEventListener("click",function(){
document.body.appendChild(_this.boxDom);
_this.boxDom.style.display = "block";
// 打开遮罩层的回调
_this.options.open&&_this.options.open();
},false);

this.boxDom.addEventListener("click",function(){
this.style.display = "none";
// 关闭遮罩层的回调
_this.options.close&&_this.options.close();
},false);
}
};
// 暴露方法
window.MaskShare = MaskShare;
}(window,document));

//使用示例：
MaskShare(".immediately",{
imgSrc:"../static/img/loading_icon.gif",
boxDomStyle:{
opacity:".9"
},
imgDomStyle:{
opacity:".8"
},
open:function(){
console.log("show");
},
close:function(){
console.log("close");
}
});