René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Modules loaded through `--import` seem to use a separate ESM cache","articleBody":"### Version\r\n\r\nv18.8.0\r\n\r\n### Platform\r\n\r\nDarwin Tims-MacBook-Pro.local 21.6.0 Darwin Kernel Version 21.6.0: Wed Aug 10 14:28:23 PDT 2022; root:xnu-8020.141.5~2/RELEASE_ARM64_T6000 arm64\r\n\r\n### Subsystem\r\n\r\nECMAScript modules\r\n\r\n### What steps will reproduce the bug?\r\n\r\nWhen running the following command:\r\n\r\n    node --experimental-loader ./loader.mjs ./run.mjs\r\n\r\nGiven the following context:\r\n\r\n```js\r\n// loader.mjs\r\nimport './shared-dep.mjs';\r\nconsole.log('loaded loader.mjs');\r\n```\r\n```js\r\n// shared-dep.mjs\r\nconsole.log('loaded shared-dep.mjs');\r\n```\r\n```js\r\n// run.mjs\r\nimport './loader.mjs';\r\nimport './shared-dep.mjs';\r\nconsole.log('loaded run.mjs');\r\n```\r\n\r\nThe output is as follows:\r\n\r\n```\r\nloaded shared-dep.mjs\r\nloaded loader.mjs\r\nloaded shared-dep.mjs\r\nloaded loader.mjs\r\nloaded run.mjs\r\n```\r\n\r\nNotice how the imports from `--experimental-loader ./loader.mjs` are reloaded once they are imported from `node ./run.mjs`, while the two times that `shared-dep.mjs` is imported as a result of the latter triggers only a single load. This looks to me like we are dealing with two ESM caches here.\r\n\r\n### How often does it reproduce? Is there a required condition?\r\n\r\nSharing modules between A \u0026 B when doing `node --experimental-loader A B`.\r\n\r\n### What is the expected behavior?\r\n\r\n```\r\nloaded shared-dep.mjs\r\nloaded loader.mjs\r\nloaded run.mjs\r\n```\r\n\r\n### What do you see instead?\r\n\r\n```\r\nloaded shared-dep.mjs\r\nloaded loader.mjs\r\nloaded shared-dep.mjs\r\nloaded loader.mjs\r\nloaded run.mjs\r\n```\r\n\r\n### Additional information\r\n\r\nThe two _do_ share the same `global`.","author":{"url":"https://github.com/timmolendijk","@type":"Person","name":"timmolendijk"},"datePublished":"2022-09-09T19:15:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":11},"url":"https://github.com/44583/node/issues/44583"}