An empty database in everybody's pocket at NG-Poland

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An empty database in everybody's pocket Phil Nash NG-Poland 2016

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Phil Nash @philnash http://philna.sh [email protected]

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An empty database in everybody's pocket

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Problems

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Performance

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Offline

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Offline Poor connectivity

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Offline Poor connectivity Resiliency

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User experience

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An empty database in everybody's pocket

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The options

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LocalStorage

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LocalStorage localStorage.setItem('NG-Poland', 'Awesome');

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But...

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WebSQL?

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So...

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IndexedDB

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IndexedDB has a bad reputation

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What is IndexedDB?

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Object store

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Transactional

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Asynchronous

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Same origin policy

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Demo

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0:00 / 0:48

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0:00 / 4:36

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Open the database let db; const request = indexedDB.open("messagesTest", 1); request.onerror = (err) => console.error(err); request.onupgradeneeded = (event) => { const db = event.target.result; db.createObjectStore("messages", { keyPath: "sid" }); }; request.onsuccess = (event) => { // do other stuff } 01. 02. 03. 04. 05. 06. 07. 08.

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Add messages to the database const transaction = db.transaction(["messages"], "readwrite"); const objectStore = transaction.objectStore("messages"); const request = objectStore.put(message); request.onsuccess = (event) => console.log(event); 01. 02. 03. 04.

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Read messages from the database request.onsuccess = (event) => { db = event.target.result; const transaction = db.transaction(["messages"]); const objectStore = transaction.objectStore("messages"); objectStore.openCursor().onsuccess = (event) => { const cursor = event.target.result; if (cursor) { messageList.addMessage(cursor.value); cursor.continue(); } else { renderMessages(messageList); } }; }; 01. 02. 03. 04. 05. 06. 07. 08. 09. 10. 11. 12. 13. 14.

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There's more!

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Indexes

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Indexes request.onupgradeneeded = (event) => { const db = event.target.result; const objectStore = db.createObjectStore('messages', { keyPath: 'sid' }); objectStore.createIndex('dateUpdated', 'dateUpdated'); }; 01. 02. 03. 04. 05. 06. 07.

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Indexes const transaction = db.transaction(['messages']); const objectStore = transaction.objectStore('messages'); const index = objectStore.index('dateUpdated'); index.openCursor().onsuccess = (event) => { // do stuff } 01. 02. 03. 04. 05. 06.

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Upgrades

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Upgrades request.onupgradeneeded = (event) => { const db = event.target.result; db.createObjectStore("messages", { keyPath: "sid" }); }; 01. 02. 03. 04.

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Upgrades request.onupgradeneeded = (event) => { const db = event.target.result; if (event.oldVersion < 1) { db.createObjectStore("messages", { keyPath: "sid" }); } if (event.oldVersion < 2) { db.createObjectStore("channels", { keyPath: "sid" }); } }; 01. 02. 03. 04. 05. 06. 07. 08. 09.

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Bugs

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Safari

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Libraries!

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idb-keyval localForage idb Dexie PouchDB

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angular2-indexeddb

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angular2-indexedDB import {AngularIndexedDB} from 'angular2-indexeddb'; const db = new AngularIndexedDB('messageStore', 1); db.createStore(1, (event) => { const objectStore = event.currentTarget.result; objectStore.createObjectStore('messages', { keyPath: "sid"}); }); 01. 02. 03. 04. 05. 06. 07. 08.

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angular2-indexedDB db.update('messages', message).then(() => { console.log("yay!"); }, (error) => { console.error("boo!", error); }); 01. 02. 03. 04. 05.

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angular2-indexedDB db.openCursor('messages', (event) => { const cursor = event.target.result; if(cursor) { // do something with cursor.value cursor.continue(); } else { // render } }); 01. 02. 03. 04. 05. 06. 07. 08. 09.