javascript/jquery add trailing slash to url (if not present)

I added to the regex solution to accommodate query strings:

http://jsfiddle.net/hRheW/8/

url.replace(/\/?(\?|#|$)/, '/$1')

url += url.endsWith("/") ? "" : "/"

var lastChar = url.substr(-1); // Selects the last character
if (lastChar != '/') {         // If the last character is not a slash
   url = url + '/';            // Append a slash to it.
}

The temporary variable name can be omitted, and directly embedded in the assertion:

if (url.substr(-1) != '/') url += '/';

Since the goal is changing the url with a one-liner, the following solution can also be used:

url = url.replace(/\/?$/, '/');

• If the trailing slash exists, it is replaced with /.
• If the trailing slash does not exist, a / is appended to the end (to be exact: The trailing anchor is replaced with /).