jkrems

client.mjs:
  import "fs";
    [A]:
      parentResolve()
        [B]:
          parentResolve()
            [native]:
              'fs' -> 'node:fs'
          'fs' -> $BWRAP = 'data:import "node:fs";'
      'fs' -> $AWRAP = 'data:import "$BWRAP";'

jkrems

> make -j4
/Applications/Xcode-beta.app/Contents/Developer/usr/bin/make -C out BUILDTYPE=Release V=0
  LD_LIBRARY_PATH=/Users/jkrems/Projects/node/node/out/Release/lib.host:/Users/jkrems/Projects/node/node/out/Release/lib.target:$LD_LIBRARY_PATH; export LD_LIBRARY_PATH; cd ../.; mkdir -p /Users/jkrems/Projects/node/node/out/Release/obj/gen; python tools/js2c.py lib/internal/bootstrap/environment.js lib/internal/bootstrap/loaders.js lib/internal/bootstrap/node.js lib/internal/bootstrap/pre_execution.js lib/internal/per_context/primordials.js lib/internal/per_context/setup.js lib/internal/per_context/domexception.js lib/async_hooks.js lib/assert.js lib/buffer.js lib/child_process.js lib/console.js lib/constants.js lib/crypto.js lib/cluster.js lib/dgram.js lib/dns.js lib/domain.js lib/events.js lib/fs.js lib/http.js lib/http2.js lib/_http_agent.js lib/_http_client.js lib/_http_common.js lib/_http_incoming.js lib/_http_outgoing.js lib/_http_server.js lib/https.js lib/inspector.js lib/module.js lib/net.js lib/os.j

jkrems

'use strict';

function calculate(expression) {
  // [...]
}

jkrems

Module Resolution & Format Lookup

Motivating Examples

• A package (react-dom) has a dedicated entrypoint `react-dom/server for code that isn't compatible with a browser environment.
• A package (angular) exposes multiple independent APIs, modeled via import paths like angular/common/http.
• A package (lodash) allows to import individual functions, e.g. lodash/map.
• A package is exclusively exposing an ESM interface.
• A package is exclusively exposing a CJS interface.
• A package is exposing both an ESM and a CJS interface.

jkrems

Moving to async/await

waterfall

function before(cb) {
  waterfall(
    f1,
    f2,
 cb

jkrems

'use strict';

const ivm = require('isolated-vm');

function handleParseJob(code) {
  return new ivm.ExternalCopy(JSON.parse(code), { transferOut: true });
}

function transferInExternalCopy(copy) {
  return copy.copy({ transferIn: true });

jkrems

Modules - History & Future

History

• Early work by Ihab Awad (Google) and Kris Kowal (FastSoft)
  • https://twitter.com/kriskowal/status/943547614158450688
  • Hermetic eval presentation: https://docs.google.com/presentation/d/1KlPxgocvzpTq44KTF4xZ6TnzGRsy628hP5he7bXVB3I/edit#slide=id.i0
• 2009-09: 2nd draft of module strawman, still very close to "closures as modules", export x = 42
  • https://esdiscuss.org/topic/hermetic-evaluation-modules-strawman

• https://docs.google.com/document/u/1/pub?id=1hNv1SHh_v_6nD1QBd6pySUJ2U5roAELzW5cqD2tt_WM

jkrems

node_modules

jkrems

// V8 6.2 required
'use strict';

const fs = require('fs');
const { Session } = require('inspector');
const { promisify } = require('util');

const session = new Session();
if (session != null) {
  session.connect();

jkrems

Getting seconds or milliseconds since January 1, 1970, 00:00:00 GMT in various languages

Second-Native

C (1972)

// ms
struct timespec spec;
clock_gettime(CLOCK_REALTIME, &spec);