Express 5: Optional Parameters : {/:param} Matching Fails When Placed at Beginning of Path

[jotpal07]

I know a similar question has been asked before here #338 but mine is a different scenario.

Previously, the route pattern :stage?/url/path worked with an optional :stage? parameter — it matched both when a stage was provided (e.g., http://localhost/devstage/url/path) and when it was omitted (e.g., http://localhost/url/path).

However, this no longer seems to work when the optional :stage parameter is placed at the beginning of the route. In this case, the route only matches if a stage name is provided — it does not match the URL when the stage is omitted.

To make both cases work, the optional parameter needs to be placed after a static segment. For example, using stagename{/:stage}/url/path allows both of the following URLs to match correctly

http://localhost/stagename/devstage/url/path
http://localhost/stagename/url/path

It appears that the optional parameter {/:stage} only works when it's not at the beginning of the route.

is this the expected behavior? And if so, is it possible to fix it so that optional parameters also work when placed at the beginning of the route?

[blakeembrey]

@jotpal07 Do you have a more clear example of what's failing? It works fine when I'm running a test locally:

> match('{/:stage}/url/path')('/url/path')
{ path: '/url/path', params: [Object: null prototype] {} }
> match('{/:stage}/url/path')('/dev/url/path')
{
  path: '/dev/url/path',
  params: [Object: null prototype] { stage: 'dev' }
}