Repository navigation
Node CLI eval option can't take unary negation operator #43397
Description
Activity
It seems that the CLI is not properly parsing its arguments?
It's rather doing it too well! It parses
-42as a flag, not as a positional argument.I agree it's a bug but I pity whoever goes in to grapple with node's option parser. You're a braver person than I am.
Before any brave soul goes on fixing this: we probably don't want
node -pe "-something"to be interpreted as anything butnode -pesomthingornode -p -e -s -o -m -e -t -h -i -n -g.I think, the proper command should look more like
node -pe -- -42, where--argument will mean that all further arguments are NOT options.Reacted by angel t.Can you explain your line of thought? Why should it be
node -pesomthingornode -p -e -s -o -m -e -t -h -i -n -g?My line of thought is based on:
- Obviously, we can't solve the issue "literally" by detecting numeric expressions
- Commonly, short options should allow stacking together (
-ab==-a -b) - Commonly, if short option requires argument, it should allow it without delimeter (
-afoo==-a foo)
Otherwise, short options should allow arbitrary order (-b -a==-a -b) - Commonly, any argument starting with dash should be parsed as option (
-a -foo -b==-a -f -o -o -b). If we need a positional argument starting (or potentially starting) with dash, we can use double dash separator (-a -b -- -foo).
Thus said, this is how I'd like to expect parsing to work:
node -e42should work the same asnode -e 42, not "bad option"
Otherwise,node -ep 42might work the same asnode -pe 42as long as it's unambiguousnode -e --throw-deprecation [...]should never attempt to evaluate--throw-deprecationas js code
node --helpdoes mention--which should indicate that following arguments are positional. However, neithernode -e -- 42ornode -- "-dashfile.js"are available.For users who prefer setting mandatory option arguments rather than positional arguments,
node --print --eval=-42already works. :)- added a commit that references this issue
on Mar 13, 2026 - added a commit that references this issue
on Mar 17, 2026 - added a commit that references this issue
on Mar 25, 2026 - added 8 commits that reference this issue
on Mar 28, 2026 - added a commit that references this issue
on Jul 29, 2026
Version
v17.9.0
Platform
Darwin [redacted] 19.6.0 Darwin Kernel Version 19.6.0: Tue Feb 15 21:39:11 PST 2022; root:xnu-6153.141.59~1/RELEASE_X86_64 x86_64
Subsystem
No response
What steps will reproduce the bug?
Execute the following:
$ node -pe "-0"And you will get back:
In fact, anything where the
-comes first, you get this message.For example, all of the following also result in the above message:
How often does it reproduce? Is there a required condition?
It's always reproducable (at least on this version and machine).
What is the expected behavior?
I'd like it to not spit back an error message and give me the evaluated value, please.
What do you see instead?
An error message detailing that the "eval" option was not given a value.
Additional information
It seems that the CLI is not properly parsing its arguments?
Prefixing the expression with
0seems to work:$ node -pe "0-42" 42As well as using a comma operator:
$ node -pe "(0, -42)" -42