Question

I’m writing a function that takes a prospective filename and validates it in order to ensure that no system disallowed characters are in the filename. These are the disallowed characters: / \ | * ? ” < >

I could obviously just use string.indexOf() to search for each special char one by one, but that’s a lot longer than it would be to just use string.search() using a regular expression to find any of those characters in the filename.

The problem is that most of these characters are considered to be part of describing a regular expression, so I’m unsure how to include those characters as actually being part of the regex itself. For example, the / character in a Javascript regex tells Javascript that it is the beginning or end of the regex. How would one write a JS regex that functionally behaves like so: filename.search(\ OR / OR | OR * OR ? OR ” OR < OR >)

Answer 1

Put your stuff in a character class like so:

[/\\|*?"<>]

You’re gonna have to escape the backslash, but the other characters lose their special meaning. Also, RegExp’s test() method is more appropriate than String.search in this case.

filenameIsInvalid = /[/\\|*?"<>]/.test(filename);