Validate file extension jquery

I am uploading images to a servlet. The validation whether the uploaded file is an image is done in server side only, by checking the magic numbers in the file header. Is there any way to validate the extensions in client side before submitting the form to servlet?

As soon as I hit enter it starts uploading. It's possible to check only the file extension, but user can easily rename virus. For what it's worth, here is the code to check file extension and abort if does not meet one of the valid extensions: choose invalid file and try to submit to see the alert in action. Note, the code will allow user to send without choosing file The code will validate any file input in the form, regardless of its name.

This can be done with jQuery in less lines, but I'm comfortable enough with "raw" JavaScript and the final result is the same. In case you have more files, or want to trigger the check upon changing the file and not only in form submission, use such code instead:. None of the existing answers seemed quite compact enough for the simplicity of the request. Checking if a given file input field has an extension from a set can be accomplished as follows:. There's no error checking on these to keep them short, presumably if you use them you'll make sure the input exists first and the extensions array is valid!

If you're needing to test remote urls in an input field, you can try testing a simple regex with the types that you're interested in. I should note that some popular sites like Twitter append a size attribute to the end of their images. For instance, the following would fail this test even though it's a valid image type:. Better to try with mimetype than checking extension. Because, sometimes files can be exist without it and those are working very well in linux or unix systems.

You can use the accept attribute available for input file types. Checkout MDN documentation. Another nowadays example via Array. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Validation of file extension before uploading file Ask Question. March 26, at am.

May 19, at am. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. This site uses Akismet to reduce spam. Learn how your comment data is processed.

SaveAs filePath. Catch ex As Exception. End Try. End Sub. This is useful in the case if the JavaScript is disabled on the browser running the website. You can also read my article How to enable JavaScript in asp.

Net to get the detailed knowledge. Net FileUpload control before actually uploading using jQuery. In previous articles i explained how to Show image preview before uploading through asp.

This can be done both server side and client side. But to check the file type or size of file at server size through code, file must be first uploaded into server memory which is time consuming if the size of the file is large. So it will definitely degrade the performance of our application. HTML Source. Upload only jpg, jpeg, png, gif, bmp file".

Max allowed file size is 32 kb".