querystring.stringify unexpected behavior on undefined values

[moshest]

• Version: 10
• Platform: MacOS

JSON.stringify omitting undefined values:

JSON.stringify({s: 's', i: 0, n: null, u: undefined});  
// output: {"s":"s","i":0,"n":null}

But querystring.stringify not omitting undefined values:

querystring.stringify({s: 's', i: 0, n: null, u: undefined});  
// output: s=s&i=0&n=&u=

Moreover, I think that treating nulls and undefineds the same way is less usable for the user (ie. user musts to delete properties from the object in order to filter them).

[cjihrig]

FWIW, this (what I consider to be) confusing behavior has been brought up for years - nodejs/node-v0.x-archive#7971, nodejs/node-v0.x-archive#8825, etc. I think at this point, we are stuck with the behavior.

I had proposed nodejs/node-v0.x-archive#8829 a long time ago to try to work around it in a non-breaking way. It might be worth revisiting, although I'd have to look into whether it was still relevant 5 years later 😄

[devsnek]

I think URLSearchParams are clearly the superior choice here 😄

[moshest]

@devsnek putting null or undefined values as strings is even worse!

[bnoordhuis]

I think at this point, we are stuck with the behavior.

I would say so. I believe the current behavior goes all the way back to Node.js v0.1.x. Any change would almost certainly result in ecosystem breakage.

It might be good to document it though. I'll add labels.

@moshest You want to send a pull request?

[moshest]

Where are the docs?

[bnoordhuis]

@moshest doc/api/querystring.md

[moshest]

Done.

[moshest]

If anyone needs way to filter empty values (including empty strings):

// replace queries like "a=1&b=&c=2&d=" to "a=1&c=2"
stringify(query).replace(/&[^=&]+=(?=&|$)/g, '')