An empty database in everybody's pocket at Front End London

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An empty database in everybody's pocket Phil Nash Front End London November 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('FEL', '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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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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Dexie const dexie = new Dexie("messageStore"); dexie.version(1).stores({ messages: 'sid,dateUpdated' }); 01. 02. 03. 04.

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Dexie dexie.open().then((db) => { db.messages.where("sid").equals(key) .then((message) => { console.log(message.body); }); }); 01. 02. 03. 04.