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
Fluent Conf: Rise of Async JavaScript
Search
Jeremy Fairbank
March 09, 2016
Programming
6
1.1k
Fluent Conf: Rise of Async JavaScript
Jeremy Fairbank
March 09, 2016
Tweet
Share
More Decks by Jeremy Fairbank
See All by Jeremy Fairbank
Connect.Tech 2020: Advanced Cypress Testing
jfairbank
1
200
CodeMash 2020: Solving the Boolean Identity Crisis
jfairbank
1
150
CodeMash 2020: Practical Functional Programming
jfairbank
1
320
Connect.Tech 2019: Practical Functional Programming
jfairbank
0
350
Connect.Tech 2019: Solving the Boolean Identity Crisis
jfairbank
0
170
Lambda Squared 2019: Solving the Boolean Identity Crisis
jfairbank
0
120
All Things Open 2018: Practical Functional Programming
jfairbank
2
260
Connect.Tech 2018: Effective React Testing
jfairbank
1
160
Fluent Conf 2018: Building web apps with Elm Tutorial
jfairbank
2
830
Other Decks in Programming
See All in Programming
從零到一:搭建你的第一個 Observability 平台
blueswen
0
300
漸進。
ssssota
0
1.5k
Feature Flag 自動お掃除のための TypeScript プログラム変換
azrsh
PRO
4
660
型安全なDrag and Dropの設計を考える
yudppp
5
700
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
710
Cloudflare Realtime と Workers でつくるサーバーレス WebRTC
nekoya3
0
360
TypeScript エンジニアが Android 開発の世界に飛び込んだ話
yuisakamoto
6
1k
セキュリティマネジャー廃止とクラウドネイティブ型サンドボックス活用
kazumura
1
140
人には人それぞれのサービス層がある
shimabox
3
630
「兵法」から見る質とスピード
ickx
0
240
バリデーションライブラリ徹底比較
nayuta999999
1
560
20250528 AWS Startupイベント登壇資料:AIコーディングの取り組み
procrustes5
0
130
Featured
See All Featured
Imperfection Machines: The Place of Print at Facebook
scottboms
267
13k
The Myth of the Modular Monolith - Day 2 Keynote - Rails World 2024
eileencodes
25
2.8k
Intergalactic Javascript Robots from Outer Space
tanoku
271
27k
Chrome DevTools: State of the Union 2024 - Debugging React & Beyond
addyosmani
6
670
The Cult of Friendly URLs
andyhume
78
6.4k
Why Our Code Smells
bkeepers
PRO
337
57k
[RailsConf 2023] Rails as a piece of cake
palkan
55
5.6k
Creating an realtime collaboration tool: Agile Flush - .NET Oxford
marcduiker
30
2.1k
Fantastic passwords and where to find them - at NoRuKo
philnash
51
3.3k
Visualization
eitanlees
146
16k
Done Done
chrislema
184
16k
Facilitating Awesome Meetings
lara
54
6.4k
Transcript
the RISEof async… JavaScript Jeremy Fairbank blog.jeremyfairbank.com @elpapapollo | gh/jfairbank
We help brands excel. pushagency.io Your website, SimplyBuilt. simplybuilt.com
None
None
None
None
“Call me maybe?”
Async API Callback
Callback fetchUserById(1, function(err, user) { if (err) { console.error('Could not
retrieve user'); } else { console.log(user); } });
}); }); }); }); }); }); Callback Callback Callback Callback
Callback Callback
function fetchCustomerNameForOrder(orderId, done, fail) { fetchOrder(orderId, function(err, order) { if
(err) { logError(err); fail(err); } else { fetchCustomer( order.customerId, function(err, customer) { if (err) { logError(err); fail(err); } else { done(customer.name); } } ); } }); }
function fetchCustomerNameForOrder(orderId, done, fail) { fetchOrder(orderId, function(err, order) { if
(err) { logError(err); fail(err); } else { fetchCustomer( order.customerId, function(err, customer) { if (err) { logError(err); fail(err); } else { done(customer.name); } } ); } }); }
function fetchCustomerNameForOrder(orderId, done, fail) { fetchOrder(orderId, function(err, order) { if
(err) { logError(err); fail(err); } else { fetchCustomer( order.customerId, function(err, customer) { if (err) { logError(err); fail(err); } else { done(customer.name); } } ); } }); }
Async API ?
Promise function fetchCustomerNameForOrder(orderId) { return fetchOrder(orderId) .then(order => fetchCustomer(order.customerId)) .then(customer
=> customer.name); }
.then(...) .then(...) .then(...) .then(...) .then(...) .then(...) .then(...) .then(...)
Error Error Error Error
function fetchCustomerNameForOrder(orderId) { return fetchOrder(orderId) .then(order => fetchCustomer(order.customerId)) .then(customer =>
customer.name) .catch(err => { logError(err); throw err; }); }
Getting there…
• Readable, synchronous program flow • Nonblocking • Use native
flow control constructs
async function fetchCustomerNameForOrder(orderId) { try { const order = await
fetchOrder(orderId); const customer = await fetchCustomer(order.customerId); return customer.name; } catch (err) { logError(err); throw err; } }
async function fetchCustomerNameForOrder(orderId) { try { const order = await
fetchOrder(orderId); const customer = await fetchCustomer(order.customerId); return customer.name; } catch (err) { logError(err); throw err; } }
async function fetchCustomerNameForOrder(orderId) { try { const order = await
fetchOrder(orderId); const customer = await fetchCustomer(order.customerId); return customer.name; } catch (err) { logError(err); throw err; } }
async function fetchCustomerNameForOrder(orderId) { try { const order = await
fetchOrder(orderId); const customer = await fetchCustomer(order.customerId); return customer.name; } catch (err) { logError(err); throw err; } }
None
Await
function fetchOrder(orderId) { return fetch(`/orders/${orderId}`) .then(response => response.json()); } function
printOrder(orderId) { fetchOrder(orderId) .then(order => console.log(order)); }
function fetchOrder(orderId) { return fetch(`/orders/${orderId}`) .then(response => response.json()); } async
function printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order); }
async printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order); }
fetchOrder(orderId) order
async printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order); }
await
async printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order); }
await order
await order
await order
async printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order); }
?
async function printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order);
} printOrder(1); Invoke
async function printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order);
} printOrder(1); Encounter await
async function printOrder(orderId) { const order = await fetchOrder(orderId); console.log(order);
} printOrder(1); Wrap in Promise.resolve
Wrap in Promise.resolve async function printOrder(orderId) { const promise =
Promise.resolve(fetchOrder(orderId)); console.log(order); } printOrder(1);
async function printOrder(orderId) { const promise = Promise.resolve(fetchOrder(orderId)); console.log(order); }
printOrder(1); Wrap rest with then callback
async function printOrder(orderId) { const promise = Promise.resolve(fetchOrder(orderId)); return promise.then(order
=> { console.log(order); return Promise.resolve(undefined); }); } printOrder(1); Wrap rest with then callback
async function printOrder(orderId) { const promise = Promise.resolve(fetchOrder(orderId)); return promise.then(order
=> { console.log(order); return Promise.resolve(undefined); }); } printOrder(1); Wrap implicit return with Promise.resolve
function fetchCustomerNameForOrder(orderId) { return Promise.resolve(fetchOrder(orderId)) .then(order => { return Promise.resolve(fetchCustomer(order.customerId))
.then(customer => { return Promise.resolve(customer.name); }); }); } ?
async function meaningOfLife() { return 42; } meaningOfLife() === 42;
???
async function meaningOfLife() { return 42; } function meaningOfLife() {
return Promise.resolve(42); } meaningOfLife() .then(answer => answer === 42);
Exceptional Situations
async function printOrder(orderId) { try { const order = await
fetchOrder(orderId); console.log(order); } catch (e) { console.log('Error retrieving order', e); } }
async function printOrder(orderId) { try { const order = await
fetchOrder(orderId); console.log(order); } catch (e) { console.log('Error retrieving order', e); } } ?
function fetchOrder(orderId) { return fetch(`/orders/${orderId}`) .then(resp => { if (resp.status
=== 404) { throw new Error('Order not found'); } return resp.json(); }); }
function fetchOrder(orderId) { return new Promise((resolve, reject) => { $.get(`/orders/${orderId}`)
.done(order => resolve(order)) .fail(resp => { if (resp.status === 404) { reject(new Error('Order not found')); } }); }); }
Error Error Error Error
Regain Control
async function findOrCreateOrder(orderId) { let order; if (await orderExists(orderId)) {
order = await fetchOrder(orderId); } else { order = await createOrder(); } return order; }
async function findOrCreateOrder(orderId) { let order; if (await orderExists(orderId)) {
order = await fetchOrder(orderId); } else { order = await createOrder(); } return order; }
async function printOrders(orderIds) { for (const id of orderIds) {
const order = await fetchOrder(id); console.log(order); } }
async function printOrders(orderIds) { for (const id of orderIds) {
const order = await fetchOrder(id); console.log(order); } }
async function printOrders(orderIds) { for (const id of orderIds) {
const order = await fetchOrder(id); console.log(order); } } Problem?
async function printOrders(orderIds) { for (const id of orderIds) {
const order = await fetchOrder(id); console.log(order); } } printOrders([1, 2, 3]);
printOrders([1, 2, 3]); await fetchOrder(1); await fetchOrder(2); await fetchOrder(3);
printOrders([1, 2, 3]); await fetchOrder(1); await fetchOrder(2); await fetchOrder(3);
printOrders([1, 2, 3]); await fetchOrder(1); await fetchOrder(2); await fetchOrder(3);
async function printOrders(orderIds) { const orders = await Promise.all( orderIds.map(fetchOrder)
); orders.forEach(order => console.log(order)); }
async function printOrders(orderIds) { const orders = await Promise.all( orderIds.map(fetchOrder)
); orders.forEach(order => console.log(order)); }
printOrders([1, 2, 3]); await Promise.all([ fetchOrder(1), fetchOrder(2), fetchOrder(3) ]);
printOrders([1, 2, 3]); Demo rise.of.async.jeremyfairbank.com
None
$ npm install --save-dev \ babel-core \ babel-cli \ babel-preset-es2015
\ babel-plugin-syntax-async-functions \ babel-plugin-transform-regenerator \ babel-plugin-transform-runtime
.babelrc { "presets": ["es2015"], "plugins": [ "syntax-async-functions", "transform-regenerator", "transform-runtime" ]
}
$ node_modules/.bin/babel-node myAsyncFile.js
• tc39.github.io/ecmascript-asyncawait/ • github.com/tc39/ecmascript-asyncawait • github.com/tc39/ecma262 Resources
THANKS! Jeremy Fairbank blog.jeremyfairbank.com @elpapapollo | gh/jfairbank speakerdeck.com/jfairbank/fluent-conf-rise-of-async-javascript SLIDES: github.com/jfairbank/rise-of-async-js-talk
CODE: