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拉菜單的屬性
length 表示選項(xiàng)<option>的個(gè)數(shù)
selected 布爾值,表示選項(xiàng)<option>是否被選中
SelectedIndex 被選中的選項(xiàng)序號(hào),如果沒(méi)有被選中則為-1,對(duì)于多選下拉菜單而言,返回被選中的第一個(gè)選項(xiàng)序號(hào)。從0開(kāi)始計(jì)數(shù)
text 選項(xiàng)的文本(它是option專(zhuān)有的屬性)
value 選項(xiàng)的value值
type 下拉菜單的類(lèi)型。單選返回select-one,多選返回select-multiple
options 獲取選項(xiàng)的數(shù)組,列如oSelectBox.options[2]表示下拉菜單oSelectBox中的第3項(xiàng)
訪(fǎng)問(wèn)選中項(xiàng)
下拉菜單(單選):
<html>
<head>
<title>下拉菜單,單選</title>
<style>
<!--
form{
padding:0px; margin:0px;
font:14px Arial;
}
-->
</style>
<script language="javascript">
function checkSingle(){
var oForm = document.forms["myForm1"];
var oSelectBox = oForm.constellation;
var iChoice = oSelectBox.selectedIndex; //獲取選中項(xiàng)
alert("您選中了" + oSelectBox.options[iChoice].text); //下拉菜單,單選
}
</script>
</head>
<body>
<form method="post" name="myForm1">
<label for="constellation">星座:</label>
<p>
<select id="constellation" name="constellation">
<option value="Aries" selected="selected">白羊</option>
<option value="Taurus">金牛</option>
<option value="Gemini">雙子</option>
<option value="Cancer">巨蟹</option>
<option value="Leo">獅子</option>
<option value="Virgo">處女</option>
<option value="Libra">天秤</option>
<option value="Scorpio">天蝎</option>
<option value="Sagittarius">射手</option>
<option value="Capricorn">摩羯</option>
<option value="Aquarius">水瓶</option>
<option value="Pisces">雙魚(yú)</option>
</select>
</p>
<input type="button" onclick="checkSingle()" value="查看選項(xiàng)" />
</form>
</body>
</html>
下拉菜單(多選):
<html>
<head>
<title>下拉菜單,多選</title>
<style>
<!--
form{
padding:0px; margin:0px;
font:14px Arial;
}
p{
margin:0px; padding:2px;
}
-->
</style>
<script language="javascript">
function checkMultiple(){
var oForm = document.forms["myForm1"];
var oSelectBox = oForm.constellation;
var aChoices = new Array();
//遍歷整個(gè)下拉菜單
for(var i=0;i<oSelectBox.options.length;i++)
if(oSelectBox.options[i].selected) //如果被選中
aChoices.push(oSelectBox.options[i].text); //壓入到數(shù)組中,可以用于單選的情況;
alert("您選了:" + aChoices.join()); //輸出結(jié)果
}
</script>
</head>
<body>
<form method="post" name="myForm1">
<label for="constellation">星座:</label>
<p>
<select id="constellation" name="constellation" multiple="multiple" style="height:180px;">
<option value="Aries">白羊</option>
<option value="Taurus">金牛</option>
<option value="Gemini">雙子</option>
<option value="Cancer">巨蟹</option>
<option value="Leo">獅子</option>
<option value="Virgo">處女</option>
<option value="Libra">天秤</option>
<option value="Scorpio">天蝎</option>
<option value="Sagittarius">射手</option>
<option value="Capricorn">摩羯</option>
<option value="Aquarius">水瓶</option>
<option value="Pisces">雙魚(yú)</option>
</select>
</p>
<input type="button" onclick="checkMultiple()" value="查看選項(xiàng)" />
</form>
</body>
</html>
通用的訪(fǎng)問(wèn)下拉菜單選中項(xiàng)的方法:
<script language="javascript">
function getSelectValue(Box){ //Box參數(shù)select標(biāo)簽的ID值
var oForm = document.forms["myForm1"];
var oSelectBox = oForm.elements[Box]; //根據(jù)參數(shù)相應(yīng)的選擇下拉菜單
if(oSelectBox.type == "select-one"){ //判斷是單選還是多選
var iChoice = oSelectBox.selectedIndex; //獲取選中項(xiàng)
alert("單選,您選中了" + oSelectBox.options[iChoice].text);
}else{
var aChoices = new Array();
//遍歷整個(gè)下拉菜單
for(var i=0;i<oSelectBox.options.length;i++)
if(oSelectBox.options[i].selected) //如果被選中
aChoices.push(oSelectBox.options[i].text); //壓入到數(shù)組中
alert("多選,您選了:" + aChoices.join()); //輸出結(jié)果
}
}
</script>
函數(shù)使用方法:
<select id="constellation1" name="constellation1">
<option value="Aries" selected="selected">白羊</option>
<option value="Taurus">金牛</option>
<option value="Gemini">雙子</option>
<option value="Cancer">巨蟹</option>
<option value="Leo">獅子</option>
<option value="Virgo">處女</option>
<option value="Libra">天秤</option>
<option value="Scorpio">天蝎</option>
<option value="Sagittarius">射手</option>
<option value="Capricorn">摩羯</option>
<option value="Aquarius">水瓶</option>
<option value="Pisces">雙魚(yú)</option>
</select>
<input type="button" onclick="getSelectValue('constellation1')" value="查看選項(xiàng)" />
添加、替換、刪除選項(xiàng)
通過(guò)構(gòu)造函數(shù)Option()直接添加value、text等信息,相當(dāng)方便
var oOption = new Option(text,value,defaultSelected,selected)
defaultSelected為布爾型值:1(true)設(shè)置下拉式表單默認(rèn)值,
selected為布爾值:1(true)表示被選中
最后兩項(xiàng)默認(rèn)值為0,如果不希望添加的選項(xiàng)被默認(rèn)選中則可以忽略,添加選項(xiàng)時(shí)通常將<select>列表的第length項(xiàng)直接設(shè)置為新的選項(xiàng),即在末尾增加。
添加選項(xiàng):
<html>
<head>
<title>添加選項(xiàng)</title>
<style>
<!--
form{padding:0px; margin:0px; font:14px Arial;}
p{margin:0px; padding:3px;}
input{margin:0px; border:1px solid #000000;}
-->
</style>
<script language="javascript">
function AddOption(Box){ //添加選項(xiàng),參數(shù)為<select>標(biāo)簽的ID值
var oForm = document.forms["myForm1"];
var oBox = oForm.elements[Box];
var oOption = new Option("乒乓球","Pingpang");
oBox.options[oBox.options.length] = oOption; //在菜單末尾添加選項(xiàng)
}
</script>
</head>
<body>
<form method="post" name="myForm1">
球類(lèi):
<p>
<select id="ball" name="ball" multiple="multiple">
<option value="Football">足球</option>
<option value="Basketball">籃球</option>
<option value="Volleyball">排球</option>
</select>
</p>
<input type="button" value="添加乒乓球" onclick="AddOption('ball');" />
</form>
</body>
</html>
替換選項(xiàng)
如果下拉菜單中的序號(hào)為已經(jīng)存在了的選項(xiàng),添加時(shí)則會(huì)自動(dòng)替換原有的選項(xiàng)
oBox.options[iNum]=oOption;//替換iNum個(gè)選項(xiàng)
<html>
<head>
<title>替換選項(xiàng)</title>
<style>
<!--
form{padding:0px; margin:0px; font:14px Arial;}
p{margin:0px; padding:3px;}
input{margin:0px; border:1px solid #000000;}
-->
</style>
<script language="javascript">
function ReplaceOption(Box,iNum){ //替換選項(xiàng),參數(shù)Box為<select>的ID值,iNum為替換的選項(xiàng)序號(hào);
var oForm = document.forms["myForm1"];
var oBox = oForm.elements[Box];
var oOption = new Option("乒乓球","Pingpang");
oBox.options[iNum] = oOption; //替換第iNum個(gè)選項(xiàng)
}
</script>
</head>
<body>
<form method="post" name="myForm1">
球類(lèi):
<p>
<select id="ball" name="ball" multiple="multiple">
<option value="Football">足球</option>
<option value="Basketball">籃球</option>
<option value="Volleyball">排球</option>
</select>
</p>
<input type="button" value="籃球替換為乒乓球" onclick="ReplaceOption('ball',1);" />
</form>
</body>
</html>
添加選項(xiàng)到具體位置
<html>
<head>
<title>添加到具體位置</title>
<style>
<!--
form{padding:0px; margin:0px; font:14px Arial;}
p{margin:0px; padding:3px;}
input{margin:0px; border:1px solid #000000;}
-->
</style>
<script language="javascript">
function AddOption(Box,iNum){
var oForm = document.forms["myForm1"];
var oBox = oForm.elements[Box];
var oOption = new Option("乒乓球","Pingpang");
oBox.insertBefore(oOption,oBox.options[iNum]);
}
</script>
</head>
<body>
<form method="post" name="myForm1">
球類(lèi):
<p>
<select id="ball" name="ball" multiple="multiple">
<option value="Football">足球</option>
<option value="Basketball">籃球</option>
<option value="Volleyball">排球</option>
</select>
</p>
<input type="button" value="添加乒乓球" onclick="AddOption('ball',1);" />
</form>
</body>
</html>
以上代碼IE7中雖然在正確的位置插入了選項(xiàng),但內(nèi)容卻沒(méi)有顯示出來(lái)(bug問(wèn)題)
兼容性更好的代碼,使用方法與以上相同;
<script language="javascript">
function AddOption(Box,iNum){
var oForm = document.forms["myForm1"];
var oBox = oForm.elements[Box];
var oOption = new Option("乒乓球","Pingpang");
//兼容IE7,先添加選項(xiàng)到最后,再移動(dòng)
oBox.options[oBox.options.length] = oOption;
oBox.insertBefore(oOption,oBox.options[iNum]);
}
</script>
注意:IE9已經(jīng)解決了bug問(wèn)題
刪除下拉菜單的選項(xiàng):
刪除下拉菜單中的某個(gè)選項(xiàng)時(shí)相對(duì)最簡(jiǎn)單的,只需要將這個(gè)選項(xiàng)設(shè)置為null即可
bBox.options[iNum]=null;
部導(dǎo)航條布局
html代碼:
<!DOCTYPE html><html><head>
<meta charset="utf-8">
<title>頭部導(dǎo)航條制作</title>
<link rel="stylesheet" type="text/css" href="css/master8.css">
</head>
<body>
<div class="navbox">
<ul class="clearfix">
<li><a href="#">首頁(yè)</a></li>
<li><a href="#">資訊</a></li>
<li><a href="#">web前端</a></li>
<li><a href="#">前端新聞</a></li>
<li><a href="#">聯(lián)系我們</a></li>
<li><a href="#">關(guān)于我們</a></li>
</ul>
</div>
</body>
</html>
用無(wú)序列表制作頭部導(dǎo)航條:
無(wú)序列表是上下布局排列的,那我們需要思考的是讓他左右布局的方式排列
左右排列的方式我們所用的是float:left;
浮動(dòng)的方法讓li
左右布局
CSS樣式:
.navbox{
width:960px;
height:40px;
margin:20pxauto;
background:#08c;
}
.navbox >ul>li{
float: left;
width:160px;
height:40px;
line-height:40px;
text-align: center;
font-size:16px;
}
鼠標(biāo)移入時(shí)實(shí)現(xiàn)顏色的變換
HTML代碼:
<div class="navbox">
<ul class="clearfix">
<li><a href="#">首頁(yè)</a></li>
<li><a href="#">資訊</a></li>
<li><a href="#">web前端</a></li>
<li><a href="#">前端新聞</a></li>
<li><a href="#">聯(lián)系我們</a></li>
<li><a href="#">關(guān)于我們</a></li>
</ul></div>
思路:
鼠標(biāo)移入時(shí)每個(gè)<li>
顯示為另一種顏色background: #00bfff;
css代碼:
.navbox ul li a{ display: block; color: #fff; background: #08c;}.navbox ul li a:hover{ text-decoration: none; background: #00bfff;}
下拉菜單實(shí)現(xiàn)
html:
<div class="navbox">
<ul class="clearfix">
<li><a href="#">首頁(yè)</a></li>
<li><a href="#">資訊</a></li>
<li><a href="#">web前端</a>
<ul class="subnav">
<li><a href="#">HTML</a></li>
<li><a href="#">CSS</a></li>
<li><a href="#">JavaScript</a></li>
</ul>
</li>
<li><a href="#">前端新聞</a></li>
<li><a href="#">聯(lián)系我們</a></li>
<li><a href="#">關(guān)于我們</a></li>
</ul>
</div>
思路:
在一級(jí)菜單web前端
下實(shí)現(xiàn)二級(jí)菜單<ul class="subnav">
html
css
JavaScript
當(dāng)鼠標(biāo)移入菜單時(shí)web前端時(shí)
顯示二級(jí)菜單,移出時(shí)隱藏;
CSS代碼實(shí)現(xiàn):
.subnav{ display: none;}/*鼠標(biāo)沒(méi)有移入“web前端”選項(xiàng)欄時(shí)二級(jí)菜單隱藏*/.navbox ul li:hover .subnav{ display: block;}/*當(dāng)鼠標(biāo)移入“web前端”選項(xiàng)欄時(shí)顯示二級(jí)菜單*/
三級(jí)菜單實(shí)現(xiàn)
HTML
<div class="navbox">
<ul class="clearfix">
<li><a href="#">首頁(yè)</a></li>
<li><a href="#">資訊</a></li>
<li><a href="#">web前端</a>
<ul class="subnav">
<li><a href="#">HTML</a></li>
<li><a href="#">CSS</a>
<ul class="threenav">
<li><a href="#">css1</a></li>
<li><a href="#">css2</a></li>
<li><a href="#">css3</a></li>
</ul>
</li>
<li><a href="#">JavaScript</a></li>
</ul>
</li>
<li><a href="#">前端新聞</a></li>
<li><a href="#">聯(lián)系我們</a></li>
<li><a href="#">關(guān)于我們</a></li>
</ul>
</div>
思路:
前面與二級(jí)菜單思路相似唯一不同的是三級(jí)菜單顯示的位置。
我們看看css的絕對(duì)定位與相對(duì)定位這篇文章
CSS代碼:
.subnav>li{ position: relative;}.threenav{ position: absolute; top: 0; left: 160px; width: 160px;}.subnav, .threenav{ display: none;}.subnav li:hover .threenav{ display: block;}
最后實(shí)現(xiàn)的效果如下圖:
圖1
圖2
圖3
*請(qǐng)認(rèn)真填寫(xiě)需求信息,我們會(huì)在24小時(shí)內(nèi)與您取得聯(lián)系。