浏览器端数据库存储方案的整理 -- indexDB 和 localStorage

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有些安全性不太重要的数据，我不想花大力气搞一台服务器，再安装mysql或者 monogdb，再写点rest接口。这也太麻烦了，浏览器里本来就有很好用的数据库。你为什么不尝试一下呢？

1. 客户端存储目前有两个方案比较

方案	优点	缺点
localStorage	简单易用，同步操作	存储容量小，一般不超过10MB
indexDB	接口都是异步的，操作不便	容量比localStorage大

如果要使用localStorage，那么存储量比较小。如果是用indexDB，那么最好找点开源库，直接封装友好的API, 来方便我们使用indexDB。

下面介绍一些很好用的的库。

2. 简介

2.1. localForage

• 离线存储， 提供强大的API封装IndexedDB,WebSQL,localStorage
• 12073 star
• https://github.com/localForag...

localforage.setItem('key', 'value', function (err) {
  // if err is non-null, we got an error
  localforage.getItem('key', function (err, value) {
    // if err is non-null, we got an error. otherwise, value is the value
  });
});

2.2. Dexie.js

• 专业封装 IndexedDB
• 3040 star
• https://github.com/dfahlander...

    const db = new Dexie('MyDatabase');

    // Declare tables, IDs and indexes
    db.version(1).stores({
        friends: '++id, name, age'
    });

      // Find some old friends
    await db.friends
        .where('age')
        .above(75)
        .toArray();

    // or make a new one
    await db.friends.add({
        name: 'Camilla',
        age: 25,
        street: 'East 13:th Street',
        picture: await getBlob('camilla.png')
    });

2.3. zangodb

• 给HTML5 IndexedDB 封装类似mongodb类似接口, 如果你熟悉mongodb, 那一定会用zangodb
• 688 star
• https://github.com/erikolson1...

let db = new zango.Db('mydb', { people: ['age'] });
let people = db.collection('people');

let docs = [
    { name: 'Frank', age: 20 },
    { name: 'Thomas', age: 33 },
    { name: 'Todd', age: 33 },
    { name: 'John', age: 28 },
    { name: 'Peter', age: 33 },
    { name: 'George', age: 28 }
];

people.insert(docs).then(() => {
    return people.find({
        name: { $ne: 'John' },
        age: { $gt: 20 }
    }).group({
        _id: { age: '$age' },
        count: { $sum: 1 }
    }).project({
        _id: 0,
        age: '$_id.age'
    }).sort({
        age: -1
    }).forEach(doc => console.log('doc:', doc));
}).catch(error => console.error(error));

2.4. JsStore

• 使用类似 sql的接口操作 indexDB
• 74 star
• https://github.com/ujjwalgupt...

var value = {
    column1: value1,
    column2: value2,
    column3: value3,
    ...
    columnN: valueN
};

connection.insert({
    into: "TABLE_NAME",
    values: [Value], //you can insert multiple values at a time

}).then(function(rowsAffected) {
    if (rowsAffected > 0) {
        alert('Successfully Added');
    }
}).catch(function(error) {
    alert(error.message);
});

2.5. minimongo

• 基于localstorage的浏览器端mongodb数据库
• 697 star
• https://github.com/mWater/min...

// Require minimongo
var minimongo = require("minimongo");

var LocalDb = minimongo.MemoryDb;

// Create local db (in memory database with no backing)
db = new LocalDb();

// Add a collection to the database
db.addCollection("animals");

doc = { species: "dog", name: "Bingo" };

// Always use upsert for both inserts and modifies
db.animals.upsert(doc, function() {
    // Success:

    // Query dog (with no query options beyond a selector)
    db.animals.findOne({ species:"dog" }, {}, function(res) {
        console.log("Dog's name is: " + res.name);
    });
});

2.6. pouchdb

• 基于indexDB的CouchDB-style浏览器端数据库
• 10599 star
• https://github.com/pouchdb/po...

var db = new PouchDB('dbname');

db.put({
  _id: '[email protected]',
  name: 'David',
  age: 69
});

db.changes().on('change', function() {
  console.log('Ch-Ch-Changes');
});

db.replicate.to('http://example.com/mydb');

2.7. lowdb

• 小型json数据库，浏览器端基于localStorage, lodash风格的接口，让它非常可爱
• 7997 star
• https://github.com/typicode/l...

import low from 'lowdb'
import LocalStorage from 'lowdb/adapters/LocalStorage'

const adapter = new LocalStorage('db')
const db = low(adapter)

db.defaults({ posts: [] })
  .write()

// Data is automatically saved to localStorage
db.get('posts')
  .push({ title: 'lowdb' })
  .write()

3. 参考

• html5-local-storage-revisited
• maximum-item-size-in-indexeddb