Parenthesis around route path

Question

I found this piece of code in a project using kraken and express

module.exports = function (router) {
    router.get('(/)', .....);
    router.get('(/nfc/read)', .....);
}

and I don't get why there are parenthesis around the routes paths.

Does it change something ? I can't find anything about it on the documentation of express and kraken. In the rest of the whole project all the other routes are normal, without parenthesis.

Answer 1

The difference between using and not using the parentheses is that when you use them then you will get the paths in req.params.

For example in this example:

let app = require('express')();
app.get('/abc', (req, res) => {
    console.log(req.params[0]);
});
app.listen(3333, () => console.log('http://localhost:3333/'));

what will be printed is undefined. But in this example:

let app = require('express')();
app.get('(/abc)', (req, res) => {
    console.log(req.params[0]);
});
app.listen(3333, () => console.log('http://localhost:3333/'));

what will be printed is /abc.

If there are more parentheses, there will be more elements in req.params. For example here:

let app = require('express')();
app.get('(/a)(bc)', (req, res) => {
    console.log(req.params[0]);
    console.log(req.params[1]);
});
app.listen(3333, () => console.log('http://localhost:3333/'));

the same /abc route would be matched but what would be printed is:

/a
bc

That is because the route is parsed as a regex and parentheses are capturing groups. See:

• https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/RegExp

Note that req.params is actually an object, not an array. This would return false:

console.log(Array.isArray(req.params));

It is just an object that happens to have numbers (actually strings like "0" and "1") as its keys.