This is my html:
<input type="text" name="folderName">
Here, I want to validate the textbox value by not allowing to key in special characters and space. But it should allow underscore.
How to validate this textbox?
You may try to use this function:
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
<script type="text/javascript">
function blockSpecialChar(e){
var k;
document.all ? k = e.keyCode : k = e.which;
return ((k > 64 && k < 91) || (k > 96 && k < 123) || k == 8 || k == 32 || (k >= 48 && k <= 57));
}
</script>
</head>
<body>
<form id="frm" runat="server">
<input type="text" name="folderName" onkeypress="return blockSpecialChar(event)"/>
</form>
</body>
</html>
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