js创建弹框（提示框，待确认框）

html,body,div,h1,h2,h3,h4,h5,h6,p,table,form,label,ol,ul,li,dl,dt,dd,img,p{margin:0; padding:0;}
html,body{text-size-adjust:none;-webkit-text-size-adjust:none;-webkit-user-select:none;}
a{color:#333; text-decoration:none;}
a,input:focus,div,select{tap-highlight-color:rgba(0,0,0,0);-webkit-tap-highlight-color:rgba(0,0,0,0);}
ul,li{list-style:none;}
.overlay{width: 100%; height: 100%; background: #000; opacity: 0.5; filter: alpha(opacity=50); position: fixed; left: 0; top: 0;z-index: 999;}
.box{width: 300px; height: 300px; background: #ccc; position: fixed; left: 50%; top: 50%;margin:-150px 0 0 -150px;  z-index: 9999; font-size: 18px; color: #000;}
.close{width: 20px; height: 20px; background: url(icon_close.png) scroll center center no-repeat; position: absolute; right: 10px; top: 10px; cursor: pointer;}

<a href="javascript:;" class="btn" id="btn1">提示框</a>
<a href="javascript:;" class="btn" id="btn2">没有关闭按钮的确认框</a>
<a href="javascript:;" class="btn" id="btn3">确认框</a>

var oBtn = document.getElementsByTagName('a');
var body = document.body || document.getElementsByTagName('body')[0]; 
var isClick,timer;
var closeBtn,popus,overlay;
//兼容PC点击事件与手机触屏事件
    if(/(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent)){   //苹果手机
        isClick = 'touchend';
        
    }else if (/(Android)/i.test(navigator.userAgent)){      //安卓手机
        isClick = 'touchend';    
    }else {      //pc
        isClick = 'click';
    }
    oBtn[0].onclick = function(){
        showBox({
            el:'<h1>我1.5秒后消失</h1>',
            time:1500
        })
    }
    oBtn[1].onclick = function(){
        showBox({
            el:'<h1>我没有关闭按钮</h1>'
        })
        
    }
    oBtn[2].onclick = function(){
        showBox({
            el:'<h1>我是h1标签</h1>',
            close:true,
            closeFn:function(){
                alert('这是个关闭回调函数');
            }
        })
        
    }
    function showBox(init){
        if(!init.el){
            return;
        }     
        popus = document.createElement('div');//弹框内容
        body.appendChild(popus);//body添加弹框    
        popus.className = 'box';
        popus.innerHTML= init.el;//弹框添加内容
        if(init.time){          //time代表过一段是时间消失
            clearTimeout(timer)
            timer=setTimeout(function(){
                body.removeChild(popus);//删除弹框内容
            },init.time);
        }else{                 //没time代表需要手动关闭弹框
            overlay = document.createElement('div');//遮罩层 
            body.appendChild(overlay);//body添加遮罩层
            overlay.className = 'overlay';
            //给遮罩层按钮绑定监听事件
            if(overlay.attachEvent){                //IE
                overlay.attachEvent('on'+isClick,isOpen)
            }else{                //标准
                overlay.addEventListener(isClick,isOpen);
            }
            function isOpen(){
                body.removeChild(overlay);//删除遮罩层
                body.removeChild(popus);//删除弹框内容
            }
            if(init.close){               //init.close代表需要关闭按钮
                closeBtn = document.createElement('span');//弹框关闭按钮
                closeBtn.className = 'close';
                popus.appendChild(closeBtn);//弹框内容添加弹框关闭按钮
                //给关闭按钮绑定监听事件
                if(closeBtn.attachEvent){                //IE
                    closeBtn.attachEvent('on'+isClick,isClose)
                }else{                //标准
                    closeBtn.addEventListener(isClick,isClose);
                }
                function isClose(){
                    body.removeChild(overlay);//删除遮罩层
                    body.removeChild(popus);//删除弹框内容
                    init.closeFn();//调用回调函数
                }
            }    
        }
    }