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分享关于两个联动下拉框的问题？
function changemenu(bigclassid)
{
document.form1.zp_smallclass.length = 0;
var locationid=bigclassid;
var i;
for (i=0;i<document.form1.hiddsmallclass.length; i++)//循环子菜单长度，如果是二级联动，取第三及的值
{
var hiddsmallvalue=document.form1.hiddsmallclass.options[i].value
if (hiddsmallvalue.substr(4,2)==locationid.substr(4,2))
{
document.form1.zp_smallclass.options[document.form1.zp_smallclass.length] = new Option(document.form1.hiddsmallclass.options[i].text,document.form1.hiddsmallclass.options[i].value);
}
}
}
为什么document.form1.zp_smallclass.length要赋值为0呢？
还有这个new Option(document.form1.hiddsmallclass.options[i].text,document.form1.hiddsmallclass.options[i].value);是建立一个下拉框的数组语句！
但是它怎么可以做出<option value=""></option>这段代码
{
document.form1.zp_smallclass.length = 0;
var locationid=bigclassid;
var i;
for (i=0;i<document.form1.hiddsmallclass.length; i++)//循环子菜单长度，如果是二级联动，取第三及的值
{
var hiddsmallvalue=document.form1.hiddsmallclass.options[i].value
if (hiddsmallvalue.substr(4,2)==locationid.substr(4,2))
{
document.form1.zp_smallclass.options[document.form1.zp_smallclass.length] = new Option(document.form1.hiddsmallclass.options[i].text,document.form1.hiddsmallclass.options[i].value);
}
}
}
为什么document.form1.zp_smallclass.length要赋值为0呢？
还有这个new Option(document.form1.hiddsmallclass.options[i].text,document.form1.hiddsmallclass.options[i].value);是建立一个下拉框的数组语句！
但是它怎么可以做出<option value=""></option>这段代码
...全文
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lcyvip 2004-08-19
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楼上的这位大哥可能没认真看我的问题，我并非那种只想要代码的人，我是想弄清楚原理！
bananasmiling 2004-08-18
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<html>
<head>
</head>
<body>
<script language="JavaScript">
<!--
var subval = new Array();
subval[0] = new Array('10','110','1','a')
subval[1] = new Array('10','111','2','b')
subval[2] = new Array('10','112','3','c')
subval[3] = new Array('10','113','4','d')
subval[4] = new Array('10','114','5','e')
subval[5] = new Array('10','115','6','f')
subval[6] = new Array('10','116','7','g')
subval[7] = new Array('10','117','8','h')
subval[8] = new Array('10','118','9','i')
subval[9] = new Array('10','119','10','j')
subval[10] = new Array('20','220','11','k')
subval[11] = new Array('20','221','12','m')
subval[12] = new Array('20','222','13','n')
subval[13] = new Array('20','223','14','o')
subval[14] = new Array('20','224','15','p')
subval[15] = new Array('20','225','16','q')
subval[16] = new Array('20','226','17','r')
subval[17] = new Array('20','227','18','s')
subval[18] = new Array('20','238','19','t')
subval[19] = new Array('20','239','20','u')
function changeselect1(locationid)
{
document.form1.s2.length = 0;
document.form1.s2.options[0] = new Option('==请选择==','');
document.form1.s3.length = 0;
document.form1.s3.options[0] = new Option('==请选择==','');
for (i=0; i<subval.length; i++)
{
if (subval[i][0] == locationid)
{document.form1.s2.options[document.form1.s2.length] = new Option(subval[i][2],subval[i][1]);}
}
}
function changeselect2(locationid)
{
document.form1.s3.length = 0;
document.form1.s3.options[0] = new Option('==请选择==','');
for (i=0; i<subval.length; i++)
{
if (subval[i][1] == locationid)
{document.form1.s3.options[document.form1.s3.length] = new Option(subval[i][3]);}
}
}
//-->
</script>
<form name="form1">
<input type="hidden" name="sid" value="a518add6895f22b4794f7abf3f314335">
三级联动：
<select name="s1" onChange="changeselect1(this.value)">
<option>==请选择==</option>
<option value="10">1-10</option>
<option value="20">11-20</option>
</select>
<select name="s2" onChange="changeselect2(this.value)">
<option>==请选择==</option>
</select>
<select name="s3">
<option>==请选择==</option>
</select>
</form>
</body>
</html>
<head>
</head>
<body>
<script language="JavaScript">
<!--
var subval = new Array();
subval[0] = new Array('10','110','1','a')
subval[1] = new Array('10','111','2','b')
subval[2] = new Array('10','112','3','c')
subval[3] = new Array('10','113','4','d')
subval[4] = new Array('10','114','5','e')
subval[5] = new Array('10','115','6','f')
subval[6] = new Array('10','116','7','g')
subval[7] = new Array('10','117','8','h')
subval[8] = new Array('10','118','9','i')
subval[9] = new Array('10','119','10','j')
subval[10] = new Array('20','220','11','k')
subval[11] = new Array('20','221','12','m')
subval[12] = new Array('20','222','13','n')
subval[13] = new Array('20','223','14','o')
subval[14] = new Array('20','224','15','p')
subval[15] = new Array('20','225','16','q')
subval[16] = new Array('20','226','17','r')
subval[17] = new Array('20','227','18','s')
subval[18] = new Array('20','238','19','t')
subval[19] = new Array('20','239','20','u')
function changeselect1(locationid)
{
document.form1.s2.length = 0;
document.form1.s2.options[0] = new Option('==请选择==','');
document.form1.s3.length = 0;
document.form1.s3.options[0] = new Option('==请选择==','');
for (i=0; i<subval.length; i++)
{
if (subval[i][0] == locationid)
{document.form1.s2.options[document.form1.s2.length] = new Option(subval[i][2],subval[i][1]);}
}
}
function changeselect2(locationid)
{
document.form1.s3.length = 0;
document.form1.s3.options[0] = new Option('==请选择==','');
for (i=0; i<subval.length; i++)
{
if (subval[i][1] == locationid)
{document.form1.s3.options[document.form1.s3.length] = new Option(subval[i][3]);}
}
}
//-->
</script>
<form name="form1">
<input type="hidden" name="sid" value="a518add6895f22b4794f7abf3f314335">
三级联动：
<select name="s1" onChange="changeselect1(this.value)">
<option>==请选择==</option>
<option value="10">1-10</option>
<option value="20">11-20</option>
</select>
<select name="s2" onChange="changeselect2(this.value)">
<option>==请选择==</option>
</select>
<select name="s3">
<option>==请选择==</option>
</select>
</form>
</body>
</html>
