import(cjs) with query strings has odd behavior #417
Description
Hello, module team. May I get help with the way to load packages without cache? I have seen a bit of odd behavior in import(cjs)
.
Copied from nodejs/node#29812
- Version: 12.11.1, 13.0.1
- Platform: Windows 10
- Subsystem: ES modules
From eslint/eslint#12333
Repro https://github.com/mysticatea/import-cjs-issue
Description
I tried to import packages without import cache. From the document, it looks like I should use query strings.
await import("x-esm") //→ Found as expected
await import("./node_modules/x-esm/index.js?q=0") //→ Found and `x-esm` re-ran as expected
await import("./node_modules/x-esm/index.js?q=1") //→ Found and `x-esm` re-ran as expected
x-esm
is an ES module package. It worked as expected.
const cjs = await import("x-cjs") //→ Found as expected
const cjs0 = await import("./node_modules/x-cjs/index.js?q=0") //→ Found but `x-cjs` didn't re-run
const cjs1 = await import("./node_modules/x-cjs/index.js?q=1") //→ Found but `x-cjs` didn't re-run
console.log(cjs === cjs0, cjs === cjs1, cjs0 === cjs1) //→ all are false but `x-cjs` didn't run three times
x-cjs
is a CJS package. The result was odd. The console.log()
in x-cjs
package ran only one time, but the returned values are different for each query string.
I found the entry of x-cjs
in require.cache
. However, the cache entry is odd as well. It's different from require("x-cjs")
, the entry doesn't have parent
property and the module.children
of test.js
is still empty.
Anyway, I tried to remove the cache entry.
console.log("---- remove 'require.cache' ----")
delete require.cache[require.resolve("x-cjs")]
await import("x-cjs") //→ Found but `x-cjs` didn't re-run
await import("./node_modules/x-cjs/index.js?q=0") //→ Found but `x-cjs` didn't re-run
await import("./node_modules/x-cjs/index.js?q=1") //→ Found but `x-cjs` didn't re-run
await import("./node_modules/x-cjs/index.js?q=2") //→ Found and `x-cjs` re-ran as expected
await import("./node_modules/x-cjs/index.js?q=3") //→ Found but `x-cjs` didn't re-run
Cryptic. I guess this behavior is:
import(cjs)
has cache apart fromrequire.cache
.- The
import(cjs)
cache is created fromrequire.cache
. - It runs CJS package only if
require.cache
entry was not found. - The
import(cjs)
cache is not removed even ifrequire.cache
entry deleted.
Therefore, I have to do the following steps if I want to import packages without cache.
- Find the main file of the package because I cannot put query strings to the package name.
const url = "file:" + require.resolve(packageName) + uniqueQueryString;
- Import it.
const ret = await import(url);
- Delete
require.cache
entry.delete require.cache[require.resolve(packageName)];
Questions
- Is it intentional behavior that
import(cjs)
creates incompleterequire.cache
entries? - If yes, is it intentional behavior that
import(cjs)
with query strings returns different objects for the same CJS package?
I'm guessing that import(cjs)
should not create any require.cache
entries, and import(cjs)
with query strings re-runs CJS packages as same as ES packages.