分享一个discuz下拉菜单的完整js代码

大师兄 · 发表于 2017-11-21 01:54:46

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无意中发现的discuz论坛中那个“发布新贴”等下拉菜单很有点特色，自动选择向上或向下显示菜单内容，对避免被其它控件遮住也有很好的处理方法（iframe）。

现把整个代码提出来，只需将整个代码复制下来保存为html文件即可，所有需要的js都在其中了。你可以运用在你的网站中，这绝对是一个成熟的方法。

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=gb2312" />
<meta http-equiv="Content-Language" content="zh-CN" />
<title>下拉菜单兼容版 </title>
<script language="JavaScript">
<!--
var userAgent = navigator.userAgent.toLowerCase();
var is_opera = userAgent.indexOf('opera') != -1 && opera.version();
var is_ie = (userAgent.indexOf('msie') != -1 && !is_opera) && userAgent.substr(userAgent.indexOf('msie') + 5, 3);
function $(id) {return document.getElementById(id);}
function isUndefined(variable) {return typeof variable == 'undefined' ? true : false;}
function doane(event) {
e = event ? event : window.event;
if(is_ie) {
e.returnValue = false;
e.cancelBubble = true;
} else if(e) {
e.stopPropagation();
e.preventDefault();
}
}
var jsmenu = new Array();
var ctrlobjclassName;
jsmenu['active'] = new Array();
jsmenu['timer'] = new Array();
jsmenu['iframe'] = new Array();
function initCtrl(ctrlobj, click, duration, timeout, layer) {
if(ctrlobj && !ctrlobj.initialized) {
ctrlobj.initialized = true;
ctrlobj.unselectable = true;
ctrlobj.outfunc = typeof ctrlobj.onmouseout == 'function' ? ctrlobj.onmouseout : null;
ctrlobj.onmouseout = function() {
if(this.outfunc) this.outfunc();
if(duration < 3) jsmenu['timer'][ctrlobj.id] = setTimeout('hideMenu(' + layer + ')', timeout);
}
ctrlobj.overfunc = typeof ctrlobj.onmouseover == 'function' ? ctrlobj.onmouseover : null;
ctrlobj.onmouseover = function(e) {
doane(e);
if(this.overfunc) this.overfunc();
if(click) {
clearTimeout(jsmenu['timer'][this.id]);
} else {
for(var id in jsmenu['timer']) {
if(jsmenu['timer'][id]) clearTimeout(jsmenu['timer'][id]);
}
}
}
}
}
function initMenu(ctrlid, menuobj, duration, timeout, layer, drag) {
if(menuobj && !menuobj.initialized) {
menuobj.initialized = true;
menuobj.ctrlkey = ctrlid;
menuobj.onclick = ebygum;
menuobj.style.position = 'absolute';
if(duration < 3) {
if(duration > 1) {
menuobj.onmouseover = function() {
clearTimeout(jsmenu['timer'][ctrlid]);
}
}
if(duration != 1) {
menuobj.onmouseout = function() {
jsmenu['timer'][ctrlid] = setTimeout('hideMenu(' + layer + ')', timeout);
}
}
}
menuobj.style.zIndex = 50;
if(is_ie) {
menuobj.style.filter += "progid:DXImageTransform.Microsoft.shadow(direction=135,color=#CCCCCC,strength=2)";
}
if(drag) {
menuobj.onmousedown = function(event) {try{menudrag(menuobj, event, 1);}catch(e){}};
menuobj.onmousemove = function(event) {try{menudrag(menuobj, event, 2);}catch(e){}};
menuobj.onmouseup = function(event) {try{menudrag(menuobj, event, 3);}catch(e){}};
}
}
}
var menudragstart = new Array();
function menudrag(menuobj, e, op) {
if(op == 1) {
if(in_array(is_ie ? event.srcElement.tagName : e.target.tagName, ['TEXTAREA', 'INPUT', 'BUTTON', 'SELECT'])) {
return;
}
menudragstart = is_ie ? [event.clientX, event.clientY] : [e.clientX, e.clientY];
menudragstart[2] = parseInt(menuobj.style.left);
menudragstart[3] = parseInt(menuobj.style.top);
doane(e);
} else if(op == 2 && menudragstart[0]) {
var menudragnow = is_ie ? [event.clientX, event.clientY] : [e.clientX, e.clientY];
menuobj.style.left = (menudragstart[2] + menudragnow[0] - menudragstart[0]) + 'px';
menuobj.style.top = (menudragstart[3] + menudragnow[1] - menudragstart[1]) + 'px';
doane(e);
} else if(op == 3) {
menudragstart = [];
doane(e);
}
}
function showMenu(ctrlid, click, offset, duration, timeout, layer, showid, maxh, drag) {
var ctrlobj = $(ctrlid);
if(!ctrlobj) return;
if(isUndefined(click)) click = false;
if(isUndefined(offset)) offset = 0;
if(isUndefined(duration)) duration = 2;
if(isUndefined(timeout)) timeout = 500;
if(isUndefined(layer)) layer = 0;
if(isUndefined(showid)) showid = ctrlid;
var showobj = $(showid);
var menuobj = $(showid + '_menu');
if(!showobj|| !menuobj) return;
if(isUndefined(maxh)) maxh = 400;
if(isUndefined(drag)) drag = false;
if(click && jsmenu['active'][layer] == menuobj) {
hideMenu(layer);
return;
} else {
hideMenu(layer);
}
var len = jsmenu['timer'].length;
if(len > 0) {
for(var i=0; i<len; i++) {
if(jsmenu['timer'][i]) clearTimeout(jsmenu['timer'][i]);
}
}
initCtrl(ctrlobj, click, duration, timeout, layer);
ctrlobjclassName = ctrlobj.className;
ctrlobj.className += ' hover';
initMenu(ctrlid, menuobj, duration, timeout, layer, drag);
menuobj.style.display = '';
if(!is_opera) {
menuobj.style.clip = 'rect(auto, auto, auto, auto)';
}
setMenuPosition(showid, offset);
if(is_ie && is_ie < 7) {
if(!jsmenu['iframe'][layer]) {
var iframe = document.createElement('iframe');
iframe.style.display = 'none';
iframe.style.position = 'absolute';
iframe.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(style=0,opacity=0)';
$('append_parent') ? $('append_parent').appendChild(iframe) : menuobj.parentNode.appendChild(iframe);
jsmenu['iframe'][layer] = iframe;
}
jsmenu['iframe'][layer].style.top = menuobj.style.top;
jsmenu['iframe'][layer].style.left = menuobj.style.left;
jsmenu['iframe'][layer].style.width = menuobj.w;
jsmenu['iframe'][layer].style.height = menuobj.h;
jsmenu['iframe'][layer].style.display = 'block';
}
if(maxh && menuobj.scrollHeight > maxh) {
menuobj.style.height = maxh + 'px';
if(is_opera) {
menuobj.style.overflow = 'auto';
} else {
menuobj.style.overflowY = 'auto';
}
}
if(!duration) {
setTimeout('hideMenu(' + layer + ')', timeout);
}
jsmenu['active'][layer] = menuobj;
}
function setMenuPosition(showid, offset) {
var showobj = $(showid);
var menuobj = $(showid + '_menu');
if(isUndefined(offset)) offset = 0;
if(showobj) {
showobj.pos = fetchOffset(showobj);
showobj.X = showobj.pos['left'];
showobj.Y = showobj.pos['top'];
showobj.w = showobj.offsetWidth;
showobj.h = showobj.offsetHeight;
menuobj.w = menuobj.offsetWidth;
menuobj.h = menuobj.offsetHeight;
if(offset < 3) {
menuobj.style.left = (showobj.X + menuobj.w > document.body.clientWidth) && (showobj.X + showobj.w - menuobj.w >= 0) ? showobj.X + showobj.w - menuobj.w + 'px' : showobj.X + 'px';
menuobj.style.top = offset == 1 ? showobj.Y + 'px' : (offset == 2 || ((showobj.Y + showobj.h + menuobj.h > document.documentElement.scrollTop + document.documentElement.clientHeight) && (showobj.Y - menuobj.h >= 0)) ? (showobj.Y - menuobj.h) + 'px' : showobj.Y + showobj.h + 'px');
} else if(offset == 3) {
menuobj.style.left = (document.body.clientWidth - menuobj.clientWidth) / 2 + document.body.scrollLeft + 'px';
menuobj.style.top = (document.body.clientHeight - menuobj.clientHeight) / 2 + document.body.scrollTop + 'px';
}
if(menuobj.style.clip && !is_opera) {
menuobj.style.clip = 'rect(auto, auto, auto, auto)';
}
}
}
function hideMenu(layer) {
if(isUndefined(layer)) layer = 0;
if(jsmenu['active'][layer]) {
try {
$(jsmenu['active'][layer].ctrlkey).className = ctrlobjclassName;
} catch(e) {}
clearTimeout(jsmenu['timer'][jsmenu['active'][layer].ctrlkey]);
jsmenu['active'][layer].style.display = 'none';
if(is_ie && is_ie < 7 && jsmenu['iframe'][layer]) {
jsmenu['iframe'][layer].style.display = 'none';
}
jsmenu['active'][layer] = null;
}
}
function fetchOffset(obj) {
var left_offset = obj.offsetLeft;
var top_offset = obj.offsetTop;
while((obj = obj.offsetParent) != null) {
left_offset += obj.offsetLeft;
top_offset += obj.offsetTop;
}
return { 'left' : left_offset, 'top' : top_offset };
}
function ebygum(eventobj) {
if(!eventobj || is_ie) {
window.event.cancelBubble = true;
return window.event;
} else {
if(eventobj.target.type == 'submit') {
eventobj.target.form.submit();
}
eventobj.stopPropagation();
return eventobj;
}
}
function menuoption_onclick_function(e) {
this.clickfunc();
hideMenu();
}
function menuoption_onclick_link(e) {
choose(e, this);
}
function menuoption_onmouseover(e) {
this.className = 'popupmenu_highlight';
}
function menuoption_onmouseout(e) {
this.className = 'popupmenu_option';
}
function choose(e, obj) {
var links = obj.getElementsByTagName('a');
if(links[0]) {
if(is_ie) {
links[0].click();
window.event.cancelBubble = true;
} else {
if(e.shiftKey) {
window.open(links[0].href);
e.stopPropagation();
e.preventDefault();
} else {
window.location = links[0].href;
e.stopPropagation();
e.preventDefault();
}
}
hideMenu();
}
}
</script>
<STYLE TYPE="text/css">
* { word-wrap: break-word; }
body { background: #FFF; text-align: center;}
body, td, input, textarea, select, button { color: #000; font: 12px/1.6em Helvetica, Arial, sans-serif; }
body, ul { margin: 0; padding: 0; }
div {width:100%;height:800px;padding-top:400px;text-align: center;}
a:link,a:visited{float:left;display: block;color:#fff;height:28px;line-height:28px;width:120px;background:#990;border:solid #CCC;border-width:3px 0;overflow:hidden;}
a:hover{background: #396;color:#222;}
.dropmenu {cursor: pointer;background: #393;}
.popupmenu_popup { text-align: left; line-height: 1.4em; overflow: hidden; border: 1px solid #ccc; background: #FFF; }
.headermenu_popup { width: 120px; }
.headermenu_popup li { float: left; width: 114px;margin:0 3px; line-height: 24px; height: 24px; overflow: hidden; }
.headermenu_popup li a:link,.headermenu_popup li a:visited{display: block;text-align: center;color:#666;width:100%;background: #fff;border:0;}
.headermenu_popup li a:hover {background: #eee;}
</STYLE>
</head>
<body>
<div>
<a href="http://www.jcodecraeer.com" id="post" class="dropmenu" onmouseover="showMenu(this.id)">发表</a>
<a href="http://www.jcodecraeer.com/a/jquery_js_ajaxjishu/2012/0531/219.html" id="my" class="dropmenu" onmouseover="showMenu(this.id)">我的</a>
<br>
<br>
<select name="" style="clear:left;float:left;">
<option value="" selected>这里是测试select会不会显示在上面
<option value="">不会
</select>
<ul class="popupmenu_popup headermenu_popup" id="post_menu" style="display: none">
<li><a href="#1">新话题</a></li>
<li><a href="#2">新投票</a></li>
<li><a href="#3">新文章</a></li>
<li><a href="#4">新商品</a></li>
<li><a href="#5">新活动</a></li>
</ul>
<ul class="popupmenu_popup headermenu_popup" id="my_menu" style="display: none">
<li><a href="#1">我的话题2</a></li>
<li><a href="#2">我的收藏2</a></li>
<li><a href="#3">我的订阅2</a></li>
<li><a href="#4">我的权限2</a></li>
<li><a href="#5">我的投票2</a></li>
<li><a href="#6">我的商品2</a></li>
<li><a href="#7">我的悬赏2</a></li>
<li><a href="#8">我的活动2</a></li>
<li><a href="#9">我的辩论2</a></li>
</ul>
</div>
</body>
</html>

复制代码

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