How to display an HTML input based on a dropdown selection in javascript
I have a webpage where the sub-category dropdown options are dynamic, which means that it's contents depend on the selected category.
How can I display a textbox when Colleges is selected in the sub-category dropdown, with javascript?
Below is my code:
<!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" />
<script language="javascript" type="text/javascript">
function dropdownlist(listindex) {
document.formname.subcategory.options.length = 0;
switch (listindex) {
case "Home Ware" :
document.formname.subcategory.options[0]=new Option("Select Sub-Category","");
document.formname.subcategory.options[1]=new Option("Air-Conditioners/Coolers","Air-Conditioners/Coolers");
document.formname.subcategory.options[2]=new Option("Audio/Video","Audio/Video");
document.formname.subcategory.options[3]=new Option("Beddings","Beddings");
document.formname.subcategory.options[4]=new Option("Camera","Camera");
document.formname.subcategory.options[5]=new Option("Cell Phones","Cell Phones");
break;
case "Education" :
document.formname.subcategory.options[0]=new Option("Select Sub-Category","");
document.formname.subcategory.options[1]=new Option("Colleges","Colleges");
document.formname.subcategory.options[2]=new Option("Institutes","Institutes");
document.formname.subcategory.options[3]=new Option("Schools","Schools");
document.formname.subcategory.options[4]=new Option("Tuitions","Tuitions");
document.formname.subcategory.options[5]=new Option("Universities","Universities");
break;
case "Books" :
document.formname.subcategory.options[0]=new Option("Select Sub-Category","");
document.formname.subcategory.options[1]=new Option("College Books","College Books");
document.formname.subcategory.options[2]=new Option("Engineering","Engineering");
document.formname.subcategory.options[3]=new Option("Magazines","Magazines");
document.formname.subcategory.options[4]=new Option("Medicine","Medicine");
document.formname.subcategory.options[5]=new Option("References","References");
break;
}
return true;
}
</script>
</head>
<title>Dynamic Drop Down List</title>
<body>
<form id="formname" name="formname" method="post" action="submitform.asp" >
<table width="50%" border="0" cellspacing="0" cellpadding="5">
<tr>
<td width="41%" align="right" valign="middle">Category :</td>
<td width="59%" align="left" valign="middle">
<select name="category" id="category" onchange="javascript: dropdownlist(this.options[this.selectedIndex].value);">
<option value="">Select Category</option>
<option value="Home Ware">Home Ware</option>
<option value="Education">Education</option>
<option value="Books">Books</option>
</select>
</td>
</tr>
<tr>
<td align="right" valign="middle">
Sub Category :
</td>
<td align="left开发者_如何转开发" valign="middle">
<script type="text/javascript" language="JavaScript">
document.write('<select name="subcategory"><option value="">Select Sub-Category</option></select>')
</script>
<noscript>
<select name="subcategory" id="subcategory" >
<option value="">Select Sub-Category</option>
</select>
</noscript>
</td>
</tr>
</table>
</form>
</body>
</html>
Add this JavaScript function to the page:
function changeSubcat(val)
{
var theTextbox = document.getElementById('theTextbox');
if (val == 'Colleges')
{
theTextbox.style.display = 'block';
} else {
theTextbox.style.display = 'none';
}
}
Change your subcategory drop-down to have the onchange attribute:
<select name="subcategory" onchange="javascript: changeSubcat(this.options[this.selectedIndex].value);">
Add your text box anywhere on the page:
<textarea style="display: none;" id="theTextbox"></textarea>
加载中,请稍侯......
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