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原生js实现可拖动的登录框效果

程序员文章站 2023-11-14 21:54:10
实现原理 1.onmousemove事件触发时不断更新鼠标的pagexy改变位置, 登陆框的偏移量=鼠标当前位置-鼠标到登录框边框的距离 2.onmousedown鼠...

实现原理

1.onmousemove事件触发时不断更新鼠标的pagexy改变位置,

登陆框的偏移量=鼠标当前位置-鼠标到登录框边框的距离

2.onmousedown鼠标摁下时触发事件获取鼠标到登陆框的距离,再设置true允许拖拽

3.onmouseup 鼠标弹起设置false停止拖拽

4.登录框居中显示公式:(可视区域宽高-登录框宽高)/2

5.当浏览器窗口大小变化时触发事件window.onresize 再更新登陆框居中显示

代码中有详细的注释

完整代码

<!doctype html public "-//w3c//dtd xhtml 1.0 transitional//en" "http://www.w3.org/tr/xhtml1/dtd/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>demo</title>
<style>
body,h1,h2,h3,h4,h5,h6,hr,p,blockquote,dl,dt,dd,ul,ol,li,pre,form,fieldset,legend,button,input,textarea,th,td{margin:0;padding:0;}
body,button,input,select,textarea{font:12px/1.5 tahoma,arial,\5b8b\4f53;}
h1,h2,h3,h4,h5,h6{font-size:100%;}
address,cite,dfn,em,var{font-style:normal;}
code,kbd,pre,samp{font-family:courier new,courier,monospace;}
small{font-size:12px;}
ul,ol{list-style:none;}
a{text-decoration:none;}
a:hover{text-decoration:underline;}
sup{vertical-align:text-top;}
sub{vertical-align:text-bottom;}
legend{color:#000;}
fieldset,img{border:0;}
button,input,select,textarea{font-size:100%;}
table{border-collapse:collapse;border-spacing:0;}
.clear{clear: both;float: none;height: 0;overflow: hidden;}
/*p{font-size: 100px;}*/
#btn{width: 80px;
 height: 40px;
 background: #3b7ae3;
 margin:0 auto;
 display: block;
 cursor: pointer;
 border-style: none;
 color: #fff;
 font-size: 16px;}
#mask{
 background: #000;
 opacity: 0.75;
 filter: alpha(opacity=75);
 height: 1000px;
 width: 100%;
 position: absolute;
 left: 0;
 top: 0;
 z-index: 1000;
}
#login{position: absolute; top: 100px; left: 100px; width: 400px; height: auto; border:1px solid #d5d5d5; z-index: 1001; }
.title{position: relative;background-color: #f7f7f7; cursor: move; height: 50px; line-height: 50px; font-size: 16px; color: #333; padding-left:30px;}
.close{position: absolute; top:0; right: 10px; color: #ccc;}
.content{background: #fff; padding: 15px 20px;}
.user{margin-bottom: 15px;}
.password{margin-bottom: 15px;}
.pt{display: block;
 height: 38px;
 padding-left: 15px;
 border: 1px solid #ddd;
 transition: .3s;
 font-size: 14px;
 color: #666;
 width: 343px;
 }
.sm{display: block;
 height: 48px;
 border: 1px solid #ddd;
 transition: .3s;
 font-size: 16px;
 color: #666;
 width: 360px;
 background: #3b7ae3;
 color: #fff;}
</style> 
</head> 
<body>
 <!-- <div id="mask"></div> -->
 <button id="btn" href="">登录</button>
 <!-- <div class="login" id="login">
 <div class="title" id="title">登录百度账号<a href="#" class="close">x</a></div>
 <div class="content">
 <div class="user"><input class="pt" type="input" value="手机/邮箱/用户名"></div>
 <div class="password"><input class="pt" type="input" value="密码"></div>
 <div class="submit"><input class="sm" type="submit" value="登录"></div>
 </div>
 </div> -->
<script type="text/javascript">
 function b(){ 
 //创建遮罩层div并插入body
 var mask=document.createelement("div");
 mask.id="mask";
 mask.style.height=cheight+"px";
 //宽度直接用100%在样式里
 document.body.appendchild(mask);
 //创建登录层div并插入body
 var login=document.createelement("div");
 login.id="login";
 login.innerhtml='<div class="title" id="title">登录百度账号'+'<a href="#" class="close">x</a>'+'</div>'+
 '<div class="content">'+'<div class="user">'+'<input class="pt" type="input" value="手机/邮箱/用户名">'+'</div>'+'<div class="password">'+'<input class="pt" type="input" value="密码">'+'</div>'+'<div class="submit">'+'<input class="sm" type="submit" value="登录">'+'</div>'+'</div>';
 document.body.appendchild(login);
 //窗口可视区域宽度
 var cwidth= document.documentelement.clientwidth || document.body.clientwidth;
 //窗口可视区域高度
 var cheight= document.documentelement.clientheight || document.body.clientheight;
 //登录框宽度
 var lwidth=login.offsetwidth;
 //登录框高度
 var lheight=login.offsetheight;
 //设置登录框的居中显示
 login.style.left=(cwidth-lwidth)/2+"px";
 login.style.top=(cheight-lheight)/2+"px";
 //设置遮罩层的高度
 mask.style.height=cheight+"px";
 //改变窗口大小后依然居中显示
 window.onresize=function(){
 if(document.compatmode=="css1compat"){  
cwidth=document.documentelement.clientwidth;
cheight=document.documentelement.clientheight;
 }else{  
  cwidth=document.body.clientwidth;
  cheight=document.body.clientheight;
 }
 login.style.left=(cwidth-lwidth)/2+"px";
 login.style.top=(cheight-lheight)/2+"px";
 mask.style.height=cheight+"px";
 }
 //获取拖拽容器
 var title=document.getelementbyid("title");
 var isdraging=false;
 var mouseoffsetx;
 var mouseoffsety;
 //鼠标按下事件
 title.onmousedown=function(e){
 var e=e||window.event;
 /*var el=e.srcelement;
 if(!el){
 el=e.target;//兼容火狐
 }*/
 //鼠标相对于登录框的位置
 mouseoffsetx=e.pagex-login.offsetleft;
 mouseoffsety=e.pagey-login.offsettop;
 //鼠标摁下时为true
 isdraging=true;
 /*console.log(mouseoffsety, mouseoffsetx)*/
 }
 //鼠标移动事件
 document.onmousemove=function(e){
 var e=e||window.event;
 //鼠标移动时的坐标
 var newmx=e.pagex;
 var newmy=e.pagey;
 //判断为true时可以拖拽
 if(isdraging===true){
 //登录框的偏移值=当前位置-鼠标到登录框的距离
 var loginl=newmx-mouseoffsetx;
 var logint=newmy-mouseoffsety;
 //如果left top值超过边缘时就让他等于边缘
 if(loginl<0){
 loginl=0;
 }else if(loginl>(cwidth-lwidth)){
 loginl=cwidth-lwidth;
 }
 if(logint<0){
 logint=0;
 }else if(logint>(cheight-lheight)){
 logint=cheight-lheight;
 }
 login.style.left=loginl+"px";
 login.style.top=logint+"px";
 } 
 }
 //鼠标弹起时设置为不可拖拽
 document.onmouseup=function(){
 isdraging=false;
 }
 //点击x关闭登录框和弹出层
 var close=login.getelementsbyclassname("close")[0];
 close.onclick=function(){
 document.body.removechild(mask);
 document.body.removechild(login);
 }
 }
 //点击登录弹出登录框和弹出层
 window.onload=function(){
 var btn=document.getelementbyid("btn");
 btn.onclick=function(){
 b();
 }
 }
</script> 
</body> 
</html> 

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