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import(cjs) with query strings has odd behavior #29812
Description
- Version: 12.11.1
- 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 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 expectedx-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 timesx-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-runCryptic. 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.cacheentry was not found. - The
import(cjs)cache is not removed even ifrequire.cacheentry 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.cacheentry.delete require.cache[require.resolve(packageName)];
Questions
- Is it intentional behavior that
import(cjs)creates incompleterequire.cacheentries? - 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.
Activity
mysticatea commentedon Oct 31, 2019
This issue is still valid in Node.js 13.0.1.
guybedford commentedon Mar 12, 2020
Here is how CJS modules are loaded into the ESM loader:
require(), it is injected at its path into the ESM loader (without any query string)import, it calls out to the CJS loader, which then injects the module value back.As a result: CommonJS modules loaded with query strings will not load their exports, AND query strings will not reload the module.
This is the way the design works unfortunately and it cannot really be changed. It was done this way because it was deemed important to "snapshot" CommonJS modules at their time of execution to inject them into the ESM loader.
The only way to allow the model this issue is asking for would be to remove that "snapshot" requirement, which I'm not sure is possible.
That said if it is possible - now would be the time to argue for it.
aduh95 commentedon Mar 21, 2021
Should this be closed as
known limitationnow that #35781 has landed?github-actions commentedon Mar 24, 2022
There has been no activity on this feature request for 5 months and it is unlikely to be implemented. It will be closed 6 months after the last non-automated comment.
For more information on how the project manages feature requests, please consult the feature request management document.
github-actions commentedon Apr 25, 2022
There has been no activity on this feature request and it is being closed. If you feel closing this issue is not the right thing to do, please leave a comment.
For more information on how the project manages feature requests, please consult the feature request management document.