Conditionally skip a middleware when a condition is met.

npm i express-unless --save

With existing middlewares:

var { unless } = require("express-unless");

var static = express.static(__dirname + "/public");
static.unless = unless;

app.use(static.unless({ method: "OPTIONS" }));

If you are authoring a middleware you can support unless as follow:

var { unless } = require("express-unless");

module.exports = function (middlewareOptions) {
  var mymid = function (req, res, next) {};

  mymid.unless = unless;

  return mymid;
};

• method it could be an string or an array of strings. If the request method match the middleware will not run.
• path it could be an string, a regexp or an array of any of those. It also could be an array of object which is url and methods key-pairs. If the request path or path and method match, the middleware will not run. Check Examples for usage.
• ext it could be an string or an array of strings. If the request path ends with one of these extensions the middleware will not run.
• custom it must be a function that accepts req and returns true / false. If the function returns true for the given request, the middleware will not run.
• useOriginalUrl it should be true or false, default is true. if false, path will match against req.url instead of req.originalUrl. Please refer to Express API for the difference between req.url and req.originalUrl.

Require authentication for every request unless the path is index.html.

app.use(
  requiresAuth.unless({
    path: ["/index.html", { url: "/", methods: ["GET", "PUT"] }],
  })
);

Avoid a fstat for request to routes doesnt end with a given extension.

app.use(
  static.unless(function (req) {
    var ext = url.parse(req.originalUrl).pathname.substr(-4);
    return !~[".jpg", ".html", ".css", ".js"].indexOf(ext);
  })
);

MIT 2014 - Jose Romaniello