Why dash in the query param cause unexpected behavior?

[kasir-barati]

const express = require('express')
const app = express()
app.get('/foo/:foo_bar', function (req, res) {
  res.send('hello foo')
})
app.get('/bar/:foo-bar', function (req, res) {
  res.send('hello bar')
})
app.listen(3000)

I want to know the reason. I am not disagreed or agreed with this.

curl -I localhost:3000/foo/a # 200
curl -I localhost:3000/bar/a # 404

[manjushsh]

Might be due to accessing as key where - is not supported.

Edit:

In javascript, object values can be accessed by using either . or []
When the key contains a dash, you cannot use the . notation because the - will be interpreted as "minus". This is not related to express, it's just how javascript works.

[blakeembrey]

A dash is not valid character for the key, it's just a random value. For example, you'll have the same issue with :foo~bar, :foo/bar, etc. You can verify this by making a request to /bar/a-bar and see it return a 200.

[kasir-barati]

Can you show me the piece of code which is responsible for dealing with query param?

[blakeembrey]

https://github.com/pillarjs/path-to-regexp

[kasir-barati]

https://github.com/pillarjs/path-to-regexp

Thank you so much for sharing.
I guess it should be these lines: https://github.com/pillarjs/path-to-regexp/blob/master/src/index.ts#L55-L63

Right?