esm: add import.meta.require

[marco-ippolito]

History:

• Pull request opened for import.meta.require on core modules#130
• Pull request opened for import.meta.require on core modules#130

Consider the following cjs snippet:

function getJSON(path){
  const file = require(path);
}

The equivalent in esm would be something like (more or less):

import { createRequire } from "node:module"
function getJSON(path){
  const require = createRequire(import.meta.url);
  const file = require(path);
}
// or asyncronously
async function getJSON(path){
  const file = await import(path, { with: { type: 'json' } });
}

We could improve the dx with the new import.meta.require:

function getJSON(path){
  const file = import.meta.require(path);
}

Now that we have cjs/esm interoperability we can create import.meta.require to syncronously require modules in ESM.

It's just an alias for:

import { createRequire } from 'node:module';

const require = createRequire(import.meta.url);

const foo = require('foo.js');

[nodejs-github-bot]

Review requested:

• @nodejs/loaders

[JakobJingleheimer]

Did the discussion settle on a decision around the perf implications?

[marco-ippolito]

Did the discussion settle on a decision around the perf implications?

Would be great to have some time at the collab-summit to discuss

[targos]

Is there still demand for it? I'm not against it but I don't expect many people to need it when you can usually just import the common js modules.

[ljharb]

The primary use cases I can see for this is importing JSON files, so you don't have to write all the with boilerplate; and, to leverage the CJS resolution algorithm for ergonomic reasons.

[JakobJingleheimer]

🙌 LGTM (assuming it's needed and the potential perf concern is 👍)

[guybedford]

This seems a little weakly motivated in the PR description - it would help a lot to get more background on the specific use cases this is seeking to solve.

[marco-ippolito]

This needs to go through WinterCG before landing.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.40%. Comparing base (58a7b00) to head (62df36f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #55730   +/-   ##
=======================================
  Coverage   88.40%   88.40%           
=======================================
  Files         654      654           
  Lines      187655   187667   +12     
  Branches    36111    36114    +3     
=======================================
+ Hits       165889   165914   +25     
- Misses      14996    15001    +5     
+ Partials     6770     6752   -18     

Files with missing lines	Coverage Δ
lib/internal/modules/esm/initialize_import_meta.js	100.00% <100.00%> (ø)

... and 27 files with indirect coverage changes