How can I make the browsing file upload window to show only the .jpg images?

I have a form that allow image uploading. However my code until now is not limited to images.

Please let me know how can I do this (maybe with a javascript alert box on submit) or my best solution is to let the browsing window to show onl开发者_如何学Pythony jpg gif and png images instead of the default "All files".

Thanks!

<input name="images[]" value="" type="file" class="textfield" />

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You cannot control what is shown in the browser's file upload form. The best option is to implement some client or server side validation on the file's extension.

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You can use JavaScript to validate the file extension, also you must validate in server side.

Another option is you can try SWFUpload- a flash JS library for uploading files. It has a feature to validate files type and file sizes before uploading to server. http://swfupload.org/