仓库
仓库地址：Github仓库
安装
已经发布到npm仓库，可以用npm、yarn、pnpm等等安装：
npm i json-file-database介绍
轻量级仓库，其内部实现原理就是把数组包装了一下，使得源数据改变时自动保存。
下面是Github页面上给出的示例代码，这英语也比较简单就不翻译了，毕竟是我写的Chinglish。
代码语言：javascript复制import { connect } from 'json-file-database'
/**
* The type of elements must have a `id` property
* to make them unique and sorted in the collection.
*/
type User = { id: number, name: string }
/**
* Connect the database.
* If there is not the file yet, it will create one after running this program.
*/
const db = connect({
file: './db.json',
init: {
users: [
{ id: 1, name: 'San Zhang' },
{ id: 2, name: 'Si Li' },
{ id: 3, name: 'Wu Wang' },
]
}
})
/**
* Specify the type of elements is User.
*
* You can go to the documentations to see how to customize all
* options, including the `comparator` to compare the elements.
*/
const users = db<User>('users')
/**
* Find the element with its id.
*/
console.log('The user whose id is 1:', users.find(1))
/**
* Find all elements that match given condition.
*/
console.log('All users whose id <= 2 are:', users.findAll(u => u.id <= 2))
/**
* Check whether this collection has the element.
*/
console.log('Whether the collection has a user whose id is 5:', users.has(5))
/**
* Insert an element and return whether it has been inserted.
*/
console.log('Insert a user whose id is 2:', users.insert({ id: 2, name: 'Liu Zhao' }))
/**
* List all elements.
*
* You can also use `[...users]` or `for...of` because
* it has implemented Iterable<E>.
*/
console.log('All users are:', Array.from(users))
/**
* Remove the element and return whether it has been removed.
*/
console.log('Remove the user whose id is 1:', users.remove(1))
/**
* Remove all elements that match the condition, and return the number of them.
*/
console.log('Remove all users whose id < 3, the number of them is:',
users.removeAll(u => u.id < 3))
/**
* Update the element with id, and return whether it has been updated.
*/
console.log('Update the user whose id is 3:', users.update(3, { name: 'Liu Zhao' }))特色
提供两种实现，基于数组和AVL树。
除了使用函数作为条件，导致的无法比较对象之间的大小的操作之外，所有的操作的最优时间复杂度都是O(log n)。对于数组来说，我们使用二分搜索来查找；对于AVL树来说，其实也是类似于数组的二分搜索。
它们唯一不同的地方就在于，数组在频繁插入时的复杂度就很差了。但是通常来说，我们的程序并不会频繁的进行插入操作，所以我定义的默认类型是数组，而非AVL树。
如果你想使用AVL树的实现，在创建Collection的时候指定一下即可：
const users = db<User>({
name: 'users',
type: 'avl'
})此外，我还使用了函数防抖来保存编辑过的数据，如下：
代码语言：javascript复制function getDataSaver(data: JSONData, delay: number, file: DatabaseFile, onSaved: () => void) : Save {
let timeout: NodeJS.Timeout | undefined
return (name, elements) => {
clearTimeout(timeout)
timeout = setTimeout(() => {
data[name] = elements()
file.write(JSON.stringify(data))
onSaved.apply(undefined)
}, delay)
}
}这样一来，频繁的数据更新就不会引起频繁的IO操作了。只有当数据更新停止一段时间后它才会真正地把数据写入硬盘。
