這篇文章主要介紹了js實作滑鼠點擊左上角滑動選單效果程式碼，涉及JavaScript基於滑鼠事件動態變換頁面元素樣式的技巧，具有一定參考借鑒價值，需要的朋友可以參考下，具體如下：
這裡需要滑鼠點選啟動的網頁左上角選單，不點擊不會滑出來，可以改造成二級選單。
運作效果截圖如下：
線上簡報網址如下：
http://demo.jb51.net/ js/2015/js-click-hd-show-menu-style-codes/
具體程式碼如下：
<!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>左上角导航菜单</title>
<style type="text/css">
#pMenu0 {position:absolute; top:0px; left:30px; visibility:hidden; font-family:arial,helvetica,sans-serif; font-size:18px; font-weight:bold;}
#pMenu1 {position:absolute; top:0px; left:150px; visibility:hidden; font-family:arial,helvetica,sans-serif; font-size:18px; font-weight:bold;}
#pMenu2 {position:absolute; top:0px; left:250px; visibility:hidden; font-family:arial,helvetica,sans-serif; font-size:18px; font-weight:bold;}
</style>
<script language="javascript">
function lib_bwcheck(){ //Browsercheck (needed)
this.ver=navigator.appVersion
this.agent=navigator.userAgent
this.dom=document.getElementById?1:0
this.opera5=this.agent.indexOf("Opera 5")>-1
this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom && !this.opera5)?1:0;
this.ie6=(this.ver.indexOf("MSIE 6")>-1 && this.dom && !this.opera5)?1:0;
this.ie4=(document.all && !this.dom && !this.opera5)?1:0;
this.ie=this.ie4||this.ie5||this.ie6
this.mac=this.agent.indexOf("Mac")>-1
this.ns6=(this.dom && parseInt(this.ver) >= 5) ?1:0;
this.ns4=(document.layers && !this.dom)?1:0;
this.bw=(this.ie6 || this.ie5 || this.ie4 || this.ns4 || this.ns6 || this.opera5)
return this
}
var bw=new lib_bwcheck()
var tMove=10;
var tSpeed=40
var tMoveOnScroll=true
var tShow=20
function makeMenu(obj,nest,show,move,speed){
nest=(!nest) ? "":'document.'+nest+'.'
this.el=bw.dom?document.getElementById(obj):bw.ie4?document.all[obj]:bw.ns4?eval(nest+'document.'+obj):0;
this.css=bw.dom?document.getElementById(obj).style:bw.ie4?document.all[obj].style:bw.ns4?eval(nest+'document.'+obj):0;
this.x=this.css.left||this.css.pixelLeft||this.el.offsetLeft||0
this.y=this.css.top||this.css.pixelTop||this.el.offsetTop||0
this.state=1; this.go=0; this.mup=b_mup; this.show=show; this.mdown=b_mdown;
this.height=bw.ns4?this.css.document.height:this.el.offsetHeight
this.moveIt=b_moveIt; this.move=move; this.speed=speed
this.obj = obj + "Object"; eval(this.obj + "=this")
}
var px = bw.ns4||window.opera?"":"px";
function b_moveIt(x,y){this.x=x; this.y=y; this.css.left=this.x+px; this.css.top=this.y+px;}
function b_mup(){
if(this.y>-this.height+this.show){
this.go=1; this.moveIt(this.x,this.y-this.move)
setTimeout(this.obj+".mup()",this.speed)
}else{this.go=0; this.state=1}
}
//Menu out
function b_mdown(){
if(this.y<eval(scrolled)){
this.go=1; this.moveIt(this.x,this.y+this.move)
setTimeout(this.obj+".mdown()",this.speed)
}else{this.go=0; this.state=0}
}
function moveTopMenu(num){
if(!oMenu[num].go){
if(!oMenu[num].state)oMenu[num].mup()
else oMenu[num].mdown()
}
for(i=0;i<oMenu.length;i++){
if(i!=num && !oMenu[i].state){ oMenu[i].mup()}
}
}
function checkScrolled(){
for(i=0;i<oMenu.length;i++){
if(!oMenu[i].go){
y=!oMenu[i].state?eval(scrolled):eval(scrolled)-oMenu[i].height+oMenu[i].show
oMenu[i].moveIt(oMenu[i].x,y)
}
}
if(bw.ns4||bw.ns6) setTimeout('checkScrolled()',40)
}
function topMenuInit(){
oMenu=new Array()
oMenu[0]=new makeMenu('pMenu0',"",tShow,tMove,tSpeed)
oMenu[1]=new makeMenu('pMenu1',"",tShow,tMove,tSpeed) //*
oMenu[2]=new makeMenu('pMenu2',"",20,10,20) //*
scrolled=bw.ns4||bw.ns6?"window.pageYOffset":"document.body.scrollTop"
for(i=0;i<oMenu.length;i++){
oMenu[i].moveIt(oMenu[i].x,-oMenu[i].height+oMenu[i].show)
oMenu[i].css.visibility='visible'
}
if(tMoveOnScroll) bw.ns4||bw.ns6?checkScrolled():window.onscroll=checkScrolled;
}
onload=topMenuInit;
</script>
<p id="pMenu0">
<!-- You can just replace this text with some cool images if you want -->
<a href="javascript://">链接一</a><br><br>
<a href="javascript://">链接二</a><br><br>
<a href="javascript://">链接三</a><br><br>
<a href="javascript://">链接四</a><br><br>
<a href="#" onclick="moveTopMenu(0); return false">菜单一</a>
</p>
<p id="pMenu1">
<!-- You can just replace this text with some cool images if you want -->
这是第二个菜单的内容<br><br>
<a href="#" onmouseover="moveTopMenu(1)">菜单二</a>
</p>
<p id="pMenu2">
<!-- You can just replace this text with some cool images if you want -->
这是第三个菜单的内容<br>
<a href="#" onclick="moveTopMenu(2); return false">菜单三</a>
</p>
</body>
</html>以上就是本章的全部內容，更多相關教學請訪問JavaScript影片教學！
