JavaScript定义函数后，调用时提示缺少对象

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你把code 放全。。

解决方案 »

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<script>
function changeCoverpic(){
var down_coverpic=new Array();
var down_name=new Array();
var down_url=new Array();
var down_coverpic[0]="/ganen2007/down/images/book_12.gif";
var down_name[0]="手册四";
var down_url[0]="/ganen2007/down/manual/book_12.rar";
var down_coverpic[1]="/ganen2007/down/images/book_07.gif";
var down_name[1]="手册三";
var down_url[1]="/ganen2007/down/manual/book_07.rar";
var down_coverpic[2]="/ganen2007/down/images/book_05.gif";
var down_name[2]="手册二";
var down_url[2]="/ganen2007/down/manual/book_05.rar";
var down_coverpic[3]="/ganen2007/down/images/book_03.gif";
var down_name[3]="手册一";
var down_url[3]="/ganen2007/down/manual/book_03.rar";
var down_id=document.getElementById("down_name").value;
document.getElementById("down_coverpic").src=down_coverpic[down_id];
document.getElementById("down_url").href=down_url[down_id];
alert("document.getElementById("down_coverpic").src");alert("document.getElementById("down_url").href");}
</script>
<tr>
<td bgcolor="#B8D200">
<table width="100%" height="109" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="34%" height="109" align="center">
<img src="/ganen2007/down/images/book_12.gif" width="76" height="102" id="down_coverpic" />
</td>
<td width="66%" align="center">
<table width="90%" height="77" border="0" cellpadding="0" cellspacing="0">
<tr valign="top">
<td>
<select name="down_name" id="down_name" onchange="changeCoverpic()">
<option value="0" selected>手册四</option>
<option value="1">手册三</option>
<option value="2">手册二</option>
<option value="3">手册一</option>
</select>
</td>
<td>
<a href="/ganen2007/down/manual/book_12.rar" id="down_url"><img src="images/down_06.gif" width="32" height="18" border="0" /></a>
</td>
</tr>
</table>
</td>
</tr>
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报错的行数？俺推测应该是 changeCoverpic() 内部调用时缺少对象！
<select name="down_name" id="down_name" onchange="changeCoverpic()">
这行报错。
错误内容为：缺少对象
changeCoverpic 内部写得一塌糊涂，哈function changeCoverpic()
{
    var down_coverpic=new Array();
    var down_name=new Array();
    var down_url=new Array();    down_coverpic[0]="/ganen2007/down/images/book_12.gif";
    down_name[0]="手册四";
    down_url[0]="/ganen2007/down/manual/book_12.rar";
    down_coverpic[1]="/ganen2007/down/images/book_07.gif";
    down_name[1]="手册三";
    down_url[1]="/ganen2007/down/manual/book_07.rar";
    down_coverpic[2]="/ganen2007/down/images/book_05.gif";
    down_name[2]="手册二";
    down_url[2]="/ganen2007/down/manual/book_05.rar";
    down_coverpic[3]="/ganen2007/down/images/book_03.gif";
    down_name[3]="手册一";
    down_url[3]="/ganen2007/down/manual/book_03.rar";
    var down_id=document.getElementById("down_name").value;    document.getElementById("down_coverpic").src=down_coverpic[down_id];
    document.getElementById("down_url").href=down_url[down_id];
    alert("document.getElementById("+down_coverpic+").src");
    alert("document.getElementById("+down_url+").href");
}
数组元素赋值是不要写 var ，因为那不是变量声明！！！
我晕倒，调了半天才看出来。。
你写那么多var做什么。。
<script type="text/javascript">
function changeCoverpic(){
var down_coverpic=new Array();
var down_name=new Array();
var down_url=new Array();down_coverpic[0]="/ganen2007/down/images/book_12.gif";
down_name[0]="手册四";
down_url[0]="/ganen2007/down/manual/book_12.rar";
down_coverpic[1]="/ganen2007/down/images/book_07.gif";
down_name[1]="手册三";
down_url[1]="/ganen2007/down/manual/book_07.rar";
down_coverpic[2]="/ganen2007/down/images/book_05.gif";
down_name[2]="手册二";
down_url[2]="/ganen2007/down/manual/book_05.rar";
down_coverpic[3]="/ganen2007/down/images/book_03.gif";
down_name[3]="手册一";
down_url[3]="/ganen2007/down/manual/book_03.rar";
var down_id=document.getElementById("down_name").value;
document.getElementById("down_coverpic").src=down_coverpic[down_id];
document.getElementById("down_url").href=down_url[down_id];
alert(document.getElementById('down_coverpic').src);
alert(document.getElementById('down_url').href);
}
</script>