A presentation at Codemotion Milan in in Milan, Metropolitan City of Milan, Italy by Trent Willis
FUN WITH SERVICE WORKERS @TRENTMWILLIS
ATWOOD’S LAW "ANY APPLICATION THAT CAN BE WRITTEN IN JAVASCRIPT, WILL EVENTUALLY BE WRITTEN IN JAVASCRIPT.”
FUN WITH SERVICE WORKERS
@TRENTMWILLIS
LOVE THE WEB LOVE JAVASCRIPT @TRENTMWILLIS
JAVASCRIPT CONTINUES TO EVOLVE @TRENTMWILLIS
WEB HYPERTEXT APPLICATION TECHNOLOGY WORKING GROUP @TRENTMWILLIS
WHATWG @TRENTMWILLIS
STREAMS SPEC “IF INSTALLED INSIDE THE FETCH HOOK OF A SERVICE WORKER, THIS WOULD ALLOW DEVELOPERS TO TRANSPARENTLY POLYFILL NEW IMAGE FORMATS.” @TRENTMWILLIS
POLYFILLING FILE FORMATS @TRENTMWILLIS
New Image Format @TRENTMWILLIS
New Image Format <img src=“./my-image.nif”> @TRENTMWILLIS
New Image Format <img src=“./my-image.nif”> *Can Display PNG/JPEG/GIF, Not NIF @TRENTMWILLIS
New Image Format Service Worker <img src=“./my-image.nif”> *Can Display PNG/JPEG/GIF, Not NIF @TRENTMWILLIS
New Image Format .nif Service Worker .gif <img src=“./my-image.nif”> *Can Display PNG/JPEG/GIF, Not NIF @TRENTMWILLIS
ALL CODE WILL BE AVAILABLE ONLINE @TRENTMWILLIS
navigator.serviceWorker.register(‘./service-worker.js’); @TRENTMWILLIS
self.addEventListener('fetch', (event) => {; }); @TRENTMWILLIS
self.addEventListener('fetch', (event) => {; event.respondWith(); }); @TRENTMWILLIS
self.addEventListener('fetch', (event) => {; event.respondWith(validFileFromPolyfilledFile(event.request)); }); @TRENTMWILLIS
self.addEventListener('fetch', (event) => {; if (isPolyfilledFile(event.request)) { event.respondWith(validFileFromPolyfilledFile(event.request)); validFileFromPolyfilledFile }; }); @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => { }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => { const originalResponse = await fetch(request); }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => { const originalResponse = await fetch(request); const originalData = originalResponse.blob(); // .text(), .json(), etc. }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => { const originalResponse = await fetch(request); const originalData = originalResponse.blob(); // .text(), .json(), etc. const modifiedData = polyfillTransform(originalData); }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => { const originalResponse = await fetch(request); const originalData = originalResponse.blob(); // .text(), .json(), etc. const modifiedData = polyfillTransform(originalData); const modifiedResponse = new Response(modifiedData); return modifiedResponse; }; @TRENTMWILLIS
cryptogram-naive.glitch.me @TRENTMWILLIS
html-modules-polyfill.glitch.me @TRENTMWILLIS
COMPILING CODE AT RUNTIME @TRENTMWILLIS
TYPESCRIPT AT RUNTIME @TRENTMWILLIS
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CACHE API @TRENTMWILLIS
ONLY COMPILE CHANGED FILES @TRENTMWILLIS
const compileWithCache = async (response, compile) => { }; @TRENTMWILLIS
const compileWithCache = async (response, compile) => { const cache = await caches.open(‘compile-cache'); }; @TRENTMWILLIS
const compileWithCache = async (response, compile) => { const cache = await caches.open(‘compile-cache'); if (response.headers.get('status') === '304') { }; }; @TRENTMWILLIS
const compileWithCache = async (response, compile) => { const cache = await caches.open(‘compile-cache'); if (response.headers.get('status') === '304') { return cache.match(request.url); }; }; @TRENTMWILLIS
const compileWithCache = async (response, compile) => { const cache = await caches.open(‘compile-cache'); if (response.headers.get('status') === '304') { return cache.match(request.url); }; const compiledResponse = compile(response); }; @TRENTMWILLIS
const compileWithCache = async (response, compile) => { const cache = await caches.open(‘compile-cache'); if (response.headers.get('status') === '304') { return cache.match(request.url); }; const compiledResponse = compile(response); cache.put(request.url, compiledResponse.clone()); }; @TRENTMWILLIS
const compileWithCache = async (response, compile) => { const cache = await caches.open(‘compile-cache'); if (response.headers.get('status') === '304') { return cache.match(request.url); }; const compiledResponse = compile(response); cache.put(request.url, compiledResponse.clone()); return compiledResponse; }; @TRENTMWILLIS
typescript-in-browser.glitch.me @TRENTMWILLIS
OFF THE MAIN THREAD DATA PROCESSING @TRENTMWILLIS
API JS @TRENTMWILLIS Process Here
API Service Worker UI @TRENTMWILLIS Process Here
API Service Worker Process Here UI @TRENTMWILLIS
API Web Worker Service Worker UI @TRENTMWILLIS Process Here
const transform = async (request, clientId) => { const [response, port] = await Promise.all([ fetch(request), getPortToWebWorkerFromClient(clientId) getPortToWebWorkerFromClient ]); }; @TRENTMWILLIS
const getPortToWebWorkerFromClient = async (clientId) => { const client = await self.clients.get(clientId); }; @TRENTMWILLIS
const getPortToWebWorkerFromClient = async (clientId) => { const client = await self.clients.get(clientId); return new Promise(resolve => { }); }; @TRENTMWILLIS
const getPortToWebWorkerFromClient = async (clientId) => { const client = await self.clients.get(clientId); return new Promise(resolve => { client.postMessage({}); }); }; @TRENTMWILLIS
const webWorker = new Worker('web-worker.js'); navigator.serviceWorker.onmessage = () => { }; @TRENTMWILLIS
const webWorker = new Worker('web-worker.js'); navigator.serviceWorker.onmessage = () => { const channel = new MessageChannel(); }; @TRENTMWILLIS
const webWorker = new Worker('web-worker.js'); navigator.serviceWorker.onmessage = () => { const channel = new MessageChannel(); const serviceWorker = navigator.serviceWorker.controller; serviceWorker.postMessage({port: channel.port1}, [channel.port1]); }; @TRENTMWILLIS
const webWorker = new Worker('web-worker.js'); navigator.serviceWorker.onmessage = () => { const channel = new MessageChannel(); const serviceWorker = navigator.serviceWorker.controller; serviceWorker.postMessage({port: channel.port1}, [channel.port1]); webWorker.postMessage({port: channel.port2}, [channel.port2]); }; @TRENTMWILLIS
const getPortToWebWorkerFromClient = async (clientId) => { const client = await self.clients.get(clientId); return new Promise(resolve => { client.postMessage({}); }); }; @TRENTMWILLIS
const getPortToWebWorkerFromClient = async (clientId) => { const client = await self.clients.get(clientId); return new Promise(resolve => { self.onmessage = (msg) => { self.onmessage = null; resolve(msg.data.port); }; client.postMessage({}); }); }; @TRENTMWILLIS
const transform = async (request, clientId) => { const [response, port] = await Promise.all([ fetch(request), getPortToWebWorkerFromClient(clientId) ]); }; @TRENTMWILLIS
const transform = async (request, clientId) => { const [response, port] = await Promise.all([ fetch(request), getPortToWebWorkerFromClient(clientId) ]); return new Promise(async (resolve) => { }); }; @TRENTMWILLIS
const transform = async (request, clientId) => { const [response, port] = await Promise.all([ fetch(request), getPortToWebWorkerFromClient(clientId) ]); return new Promise(async (resolve) => { port.postMessage(await response.json()); }); }; @TRENTMWILLIS
const transform = async (request, clientId) => { const [response, port] = await Promise.all([ fetch(request), getPortToWebWorkerFromClient(clientId) ]); return new Promise(async (resolve) => { port.onmessage = (msg) => { resolve(new Response([${msg.data.toString()}])); }; port.postMessage(await response.json()); }); };
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service-worker-worker.glitch.me @TRENTMWILLIS
STREAM DATA PROCESSING @TRENTMWILLIS
Original Data @TRENTMWILLIS Modified Data
BATCH BATCH DIGRA PROCESSING Encrypted Chunk Encrypted Chunk Decrypted Chunk @TRENTMWILLIS Encrypted Chunk Decrypted Chunk Encrypted Chunk Decrypted Chunk Encrypted Chunk Decrypted Chunk Encrypted Chunk Decrypted Chunk Decrypted Chunk
STREAM BATCH DIGRA PROCESSING Encrypted Chunk Encrypted Chunk Decrypted Chunk @TRENTMWILLIS Encrypted Chunk Decrypted Chunk Encrypted Chunk Decrypted Chunk Encrypted Chunk Decrypted Chunk Encrypted Chunk Decrypted Chunk Decrypted Chunk
Data Chunk Data Chunk Modified Chunk @TRENTMWILLIS Data Chunk Modified Chunk Data Chunk Modified Chunk Data Chunk Modified Chunk Data Chunk Modified Chunk Modified Chunk
Original Data Data Chunk Data Chunk Modified Chunk Data Chunk Modified Chunk @TRENTMWILLIS Modified Data Data Chunk Modified Chunk Data Chunk Modified Chunk Data Chunk Modified Chunk Modified Chunk
const validFileFromPolyfilledFile = async (request) => { const originalResponse = await fetch(request); const originalData = originalResponse.blob(); // .text(), .json(), etc. const modifiedData = polyfillTransform(originalData); const modifiedResponse = new Response(modifiedData); return modifiedResponse; }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => {; const originalResponse = await fetch(request); const transformStream = new TransformStream(new Transformer()); const transformedBody = originalResponse.body.pipeThrough( transformStream ); const transformedResponse = new Response(transformedBody); return transformedResponse; }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => {; const originalResponse = await fetch(request); const transformStream = new TransformStream(new Transformer()); const transformedBody = originalResponse.body.pipeThrough( transformStream ); const transformedResponse = new Response(transformedBody); return transformedResponse; }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => {; const originalResponse = await fetch(request); const transformStream = new TransformStream(new Transformer()); const transformedBody = originalResponse.body.pipeThrough( transformStream ); const transformedResponse = new Response(transformedBody); return transformedResponse; }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => {; const originalResponse = await fetch(request); const transformStream = new TransformStream(new Transformer()); const transformedBody = originalResponse.body.pipeThrough( transformStream ); const transformedResponse = new Response(transformedBody); return transformedResponse; }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => {; const originalResponse = await fetch(request); const transformStream = new TransformStream(new Transformer()); const transformedBody = originalResponse.body.pipeThrough( transformStream ); const transformedResponse = new Response(transformedBody); return transformedResponse; }; @TRENTMWILLIS
const validFileFromPolyfilledFile = async (request) => {; const originalResponse = await fetch(request); const transformStream = new TransformStream(new Transformer()); Transformer const transformedBody = originalResponse.body.pipeThrough( transformStream ); const transformedResponse = new Response(transformedBody); return transformedResponse; }; @TRENTMWILLIS
class Transformer {; async start() {}; async transform() {}; async flush() {}; }; @TRENTMWILLIS
cryptogram-streaming.glitch.me @TRENTMWILLIS
POLYFILLING FILE FORMATS SERVICE WORKERS COMPILING CODE AT RUNTIME WEB ASSEMBLY OFF THE MAIN THREAD DATA PROCESSING STREAM DATA PROCESSING @TRENTMWILLIS STREAMS ESNEXT WEB COMPONENTS AND MORE!
EXPERIMENT & HAVE FUN WITH JAVASCRIPT! *ALSO, GLITCH IS GREAT FOR EXPERIMENTS! @TRENTMWILLIS
QUESTIONS? @TRENTMWILLIS
Service Workers have given modern web applications tremendous power. They are most known for allowing apps to serve content offline and provide native-like functionality, such as receiving push notifications, but they can do so much more! In this talk, we'll explore some less talked about but exciting uses of Service Workers, such as polyfilling new file formats, transpiling code at load-time, and even doing streaming, data-processing off the main thread with other workers.
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