Validate file extension before upload

Question

I want to validate the file extension before upload so,I create the fileUpload control as following

<asp:FileUpload ID="FileUpload1" runat="server" OnChange="return validateFileExtension(this)"/>

and create java script to validate extension of file before upload

<script lang="javascript" type="text/javascript">
var validFileExtensions = [".txt", ".TXT"];
function ValidateFileUpload(Source, args) {
var fuData = document.getElementById('<%= FileUpload1.ClientID%>');
var FileUploadPath = fuData.value;
if (FileUploadPath == '') {
// There is no file selected 
args.IsValid = false;
}
else {
var Extension = FileUploadPath.substring(FileUploadPath.lastIndexOf('.') + 1).toLowerCase();
if (Extension == "txt" || Extension == "TXT") {
args.IsValid = true; // Valid file type
FileUploadPath == '';
 }
 else {
 alert("Please upload only text file")
 }
 }
 }
</script>

and I got 0x800a1391 - Javascript runtime error: 'validateFileExtension' is undefined

change validateFileExtension() to ValidateFileUpload() as OnChange="return validateFileExtension(this) accepts a function and validateFileExtension() is not a function — CodingDefined
– CodingDefined, Commented Jun 10, 2015 at 5:20

chris97ong · Accepted Answer · 2015-06-10 05:46:30Z

0

<asp:FileUpload ID="FileUpload1" runat="server" OnChange="return ValidateFileUpload(this)"/>

ValidateFileUpload instead of validateFileExtension

edited Jun 10, 2015 at 5:46

answered Jun 10, 2015 at 5:15

chris97ong

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