Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
mjs
Search
Yosuke Furukawa
PRO
April 24, 2018
Programming
4
1.1k
mjs
We are JavaScripters で発表した .mjs の話です。
Yosuke Furukawa
PRO
April 24, 2018
Tweet
Share
More Decks by Yosuke Furukawa
See All by Yosuke Furukawa
Node.js, Deno, Bun 最新動向とその所感について
yosuke_furukawa
PRO
7
3.5k
Welcome JSConf.jp 2024
yosuke_furukawa
PRO
1
4k
tc39 x jsconf.jp Panel Discussion 2024
yosuke_furukawa
PRO
0
220
Removing Corepack
yosuke_furukawa
PRO
9
1.6k
JavaScript Runtime とはなにか
yosuke_furukawa
PRO
15
2.8k
Strip Types と Storage
yosuke_furukawa
PRO
4
400
Module Harmony について
yosuke_furukawa
PRO
3
1.7k
LTのやり方
yosuke_furukawa
PRO
16
2.6k
AppRouter Panel Talk
yosuke_furukawa
PRO
3
800
Other Decks in Programming
See All in Programming
Spring gRPC で始める gRPC 入門 / Introduction to gRPC with Spring gRPC
mackey0225
0
140
Proxmoxをまとめて管理できるコンソール作ってみました
karugamo
1
410
Parallel::Pipesの紹介
skaji
2
870
コンポーネントライブラリで実現する、アクセシビリティの正しい実装パターン
schktjm
1
670
技術懸念に立ち向かい 法改正を穏便に乗り切った話
pop_cashew
0
840
OpenNext + Hono on Cloudflare でイマドキWeb開発スタックを実現する
rokuosan
0
110
PT AI без купюр
v0lka
0
200
TypeScript エンジニアが Android 開発の世界に飛び込んだ話
yuisakamoto
6
960
❄️ tmux-nixの実装を通して学ぶNixOSモジュール
momeemt
1
120
Blueskyのプラグインを作ってみた
hakkadaikon
1
290
【TSkaigi 2025】これは型破り?型安全? 真実はいつもひとつ!(じゃないかもしれない)TypeScript クイズ〜〜〜〜!!!!!
kimitashoichi
1
300
tsconfigのオプションで変わる型世界
keisukeikeda
1
130
Featured
See All Featured
Exploring the Power of Turbo Streams & Action Cable | RailsConf2023
kevinliebholz
32
5.8k
Rails Girls Zürich Keynote
gr2m
94
13k
YesSQL, Process and Tooling at Scale
rocio
172
14k
Keith and Marios Guide to Fast Websites
keithpitt
411
22k
ReactJS: Keep Simple. Everything can be a component!
pedronauck
667
120k
RailsConf & Balkan Ruby 2019: The Past, Present, and Future of Rails at GitHub
eileencodes
137
34k
Gamification - CAS2011
davidbonilla
81
5.3k
Optimizing for Happiness
mojombo
378
70k
A Modern Web Designer's Workflow
chriscoyier
693
190k
The Pragmatic Product Professional
lauravandoore
35
6.7k
Bash Introduction
62gerente
614
210k
Designing Experiences People Love
moore
142
24k
Transcript
.mjs 2018/04/24 We are JavaScripters!! @ Recruit Technologies
Twitter: @yosuke_furukawa Github: yosuke-furukawa
Node.js v10 Release (maybe tomorrow)
Node.js v10 Notable Changes • for-await-of in Stream experimental
support • ESModules experimental support • private/public class fields experimental support • fs/promises
DEMO
DEMO import fs from 'fs/promises'; import util from 'util'; async
function main() { try { const content = await fs.readFile(process.argv[2]) console.log(content.toString()) } catch(e) { console.error(e.toString()); } } main();
file name is … foo.mjs
ʊʊਓਓਓʊʊ ʼɹ.mjs !!!ɹʻ ʉʉY^Y^Yʉʉ
Yes, we have long discussion about ESM.
We need ".mjs".
Why?
Module !== Script
Module [ "strict", "top level scope", "reserved await" ] Script
[ "non strict", "global scope", ]
We need to detect which mode on load file.
if file.lastIndexOf(".mjs") { Module } else { Script }
Simple and Faster
We do not use ".js" ???? (´ɾωɾʆ)
No, 2 reasons.
Use loader option.
DEMO
DEMO const builtins = Module.builtinModules; const URL = url.URL; const
baseURL = new URL('file://'); baseURL.pathname = `${process.cwd()}/`; export function resolve(specifier, parentModuleURL = baseURL, defaultResolve) { if (builtins.includes(specifier)) { return { url: specifier, format: 'builtin' }; } const resolved = new url.URL(specifier, parentModuleURL); const ext = path.extname(resolved.pathname); return { url: resolved.href, format: 'esm' }; }
DEMO $ node —experimental-modules —loader loader.mjs file.js // file.js import
fs from 'fs'; import util from 'util'; const readFile = util.promisify(fs.readFile); async function main() { try { const content = await readFile(process.argv[2]) console.log(content.toString()) } catch(e) { console.error(e.toString()); } } main();
mode detection on flag `—mode` , package.json see: https://gist.github.com/ceejbot/b49f8789b2ab6b09548ccb72813a1054
https://docs.google.com/presentation/d/ 1xK1ana_TIxfAHX33CYVHFnJsV0If_YirLtRBBga9cv0/edit#slide=id.p
You just use ".js" if you don’t need to use
ESM.
You would be better to use ".mjs", if you need
ESM on Node.js v9-10.
You would be better to wait the conclusion, if you
want to use ES Modules in the future.
ऄ (da-soku) +
Filename Extensions YOMO-YAMA
Long long time ago… Brendan Eich saids …
)PXEPXFUIJOLFT FTpMFFYUFOTJPOTUPEFUFDU WFSTJPOT // sorry no reference… I cannot find
link 8FOFFEUPDIBOHFpMFOBNFFYUFOTJPOTUPVQHSBEF UIBUJTOJHIUNBSFʜ
*EJTMJLFNPEFT8IPEPFTOU #VUUIJTTPVOETMJLF UIF7FSTJPOJOHJTBOBOUJQBUUFSOTIJCCPMFUI*WF IFBSESFDFOUMZSF8FC4PDLFUT*UEPFTOPUSFqFDU SFBMJUZ https://esdiscuss.org/topic/no-more-modes 3FDFOUMZ *NFUXJUIUIF(PPHMF7UFBNGPSUXPGVMM EBZT0OFNFTTBHFUIBUDBNFUISPVHIMPVEBOE DMFBS
UIBU*TBJE*XPVMESFMBZUPUIFMJTU JTQMFBTF OPNPSFNPEFT
Web does not have version/mode.
All we need is feature detection.
Detectable Feature // Feature Detection if (!Array.isArray) {} if (!String.prototype.trimStart)
{}
un-detectable feature (on runtime) class A {} import / export
#foo // syntax
Modern JavaScript is difficult to detect features.
Module JavaScript is JavaScript 2.0
JavaScript is not so easy, We are JavaScripters, Every JSers
would be better to enjoy chaos.
Enjoy JS Chaos :)
Thanks