CODEWITHSUNDEEP
javascriptregex
benske
benske

Reputation: 4050

Disallow "//" in a regular expression (javascript)

I would like to disallow double forward slashes (//) in my regular expression (and thus allow single /), but my solutions doesn't work.

There also has to be NO / at the beginning and ending of a string (this work!):

/^[^/][a-z0-9-/]+[^/]$$/

this allows for example example///example// but NOT/dzkoadokzd///zdkoazaz

Now I want to disallow multiple "/" after each other. I've tried this but it doesn't work (I'm new to regular expressions):

/^[^/]([a-z0-9-]+[/]{1})+[^/]$$/

Upvotes: 0

Views: 1621

Answers (3)

RobG
RobG

Reputation: 147403

BTW, if you just want to test for slash at the start or end or double elsewhere:

function badSlash(s) {

  var re = /^\/|\/\/|\/$/;

  return re.test(s);
}

You can add another OR for whatever other patterns you don't want, e.g.

  var re = /^\/|\/\/|\/$|[^a-z0-9\/]/;

Upvotes: 1

Rafael
Rafael

Reputation: 18522

Not sure if this is a requirement, but the regex from jperovic, by using [^/] will accept any character, which is not a slash / (so it will also pass strings like "@abcd/efgh/ijkl/#" (notice the @ and #), but in other parts of the regex we try to limit the characters to [a-z0-9-]. If we want to restrict the character range for the complete string, check the regex below.

/^[a-z0-9\-](?:[a-z0-9\-]|\/(?!\/))+[a-z0-9\-]$/

Upvotes: 3

Jovan Perovic
Jovan Perovic

Reputation: 20193

/ is a meta character in regex. You need to escape it with a backslash (\/)

/^[^\/]([a-z0-9-]+[\/]{1})+[^\/]$/

Upvotes: 3

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