I was recently asked a question on the ASP.NET forum on how to prevent duplicate entries being added to a select form element. The user could type anything into a text box, then click the button and it was being added. This is another good use for jQuery! Here's the code.
<html>
<head>
<script language="javascript" type="text/javascript"
src="http://code.jquery.com/jquery-latest.js"></script>
<script language="javascript" type="text/javascript">
$(function() {
$("#Button1").click(function(e) {
var itemExists = false;
var txt = $("#Text1").val();
e.preventDefault();
$("#Select1 option").each(function() {
if ($(this).text() == $.trim(txt)) {
itemExists = true;
alert('Item already exists');
}
});
if (!itemExists) {
$("#Select1").append("<option value=\"1\">" + txt + "</option>");
$("#Text1").val('');
}
});
});
</script>
</head>
<body>
<form>
<input id="Button1" type="button" value="Add" /><br />
<input id="Text1" type="text" />
<select id="Select1">
<option value="1">Yahoo</option>
<option value="2">Microsoft</option>
<option value="3">Google</option>
</select>
</form>
</body>
</html>
Now duplicate items are not added.
Note: To ignore case, use .toLowerCase() or .toUpperCase() to compare both strings.
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