instanceof/constructor check fails if a class has different versions in node_modules

[yinrong]

• Version: any
• Platform: any
• Subsystem: not sure

suppose my runtime directory structure is

my_pkg_1/
my_pkg_1/node_modules
my_pkg_1/node_modules/[email protected]
my_pkg_1/node_modules/my_pkg_3/
my_pkg_1/node_modules/my_pkg_3/node_modules/
my_pkg_1/node_modules/my_pkg_3/node_modules/[email protected]

a check like

my_instance.constuctor === MyType

or

my_instance instanceof MyType

may fail since MyType may point to eigher [email protected] or [email protected]

I consider this may be a problem since I have experienced once during deploying process that it take quite a long time to find out the bug.

I have to remove all duplicate packages every time during deploying process. Another option of using peerDenpendencies is also not good enough I think. Should npm or node deal with this problem?

[bnoordhuis]

You probably won't be surprised the answer is 'no' - they're different functions and therefore construct different objects. npm can flatten node_modules up to a point but not if they're API-incompatible versions of the same module.

[yinrong]

@bnoordhuis thanks for comment. any suggestion on how to compare types? I still think it's a pitfall considering the result. I suppose you mean it's normal behaviour for all programming languages.

[bnoordhuis]

any suggestion on how to compare types?

My suggestion would be "don't" - they're different types, possibly with different properties and methods.

I'd work on getting all modules to agree on a single version (or compatible version range) of my_pkg_2 so that npm can deduplicate it.