Question

64

Regular Expression for Extension of File

rated 0 times [ 68] [ 4] / answers: 1 / hits: 89608 / 11 Years ago, tue, august 6, 2013, 12:00:00

I need 1 regular expression to put restrictions on the file types using it's extension.

I tried this for restricting the file type of html, .class, etc.

/(.|/)[^(html|class|js|css)]$/i

/(.|/)[^html|^class|^js|^css]$/i

I need to restrict a total of 10-15 types of files. In my application there is a field for accepted file type, and according to the requirement I have file types which is to be restricted. So I need a regular expression using negation of restricted file type only.

The plugin code is like:

$('#fileupload').fileupload('option', {

            acceptFileTypes: /(.|/)(gif|jpe?g|png|txt)$/i

});

I can specify the acceptedFileType but i have given the requirement to restrict a set of file.

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longd

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answered 11 Years ago joseluispauld · Accepted Answer

Try /^(.*.(?!(htm|html|class|js)$))?[^.]*$/i

Try it here: http://regexr.com?35rp0

It will also work with extensionless files.

As all the regexes, it's complex to explain... Let's start from the end

[^.]*$ 0 or more non . characters

( ... )? if there is something before (the last ?)



.*.(?!(htm|html|class|js)$) Then it must be any character in any number .*

                             followed by a dot .

                             not followed by htm, html, class, js (?! ... )

                             plus the end of the string $

                             (this so that htmX doesn't trigger the condition)



^ the beginning of the string

This one (?!(htm|html|class|js) is called zero width negative lookahead. It's explained at least 10 times every day on SO, so you can look anywhere :-)