json-server/lib/observer.js

[](https://github.com/typicode/json-server/actions/workflows/node.js.yml)

// Lowdb adapter to observe read/write events
export class Observer {
    #adapter;
    onReadStart = function () {
        return;
    };
    onReadEnd = function () {
        return;
    };
    onWriteStart = function () {
        return;
    };
    onWriteEnd = function () {
        return;
    };
    constructor(adapter) {
        this.#adapter = adapter;
    }
    async read() {
        this.onReadStart();
        const data = await this.#adapter.read();
        this.onReadEnd(data);
        return data;
    }
    async write(arg) {
        this.onWriteStart();
        await this.#adapter.write(arg);
        this.onWriteEnd();
    }
}