ES7 async/await

DB-class.js

class DB {

    constructor (name) {
        this.name = name;
        this.collections = {};

        this.async = function (callback, timeout) {
            return new Promise((resolve, reject) => {

                if (!callback) { return reject('Error!'); }

                setTimeout(() => {
                    resolve(callback());
                }, timeout);
            });
        };
    }

    createCollection (name) {
        return this.async(() => {
            return this.collections[name] = [];
        }, 2000);
    }

    putDoc (coll, doc) {
        return this.async(() => {
            return this.collections[coll].push(doc);
        }, 300);
    }

    getAllDocs (coll) {
        return this.async(() => {
            return this.collections[coll];
        }, 1000);
    }
}

usage.js

var db = new DB('test');

async function processThings (num) {

    try {
        await db.createCollection('things');

        for (let i = 0; i < num; i++) {
            await db.putDoc('things', { _id: i, title: 'Document_' + i });
        }

        var things = await db.getAllDocs('things');

        return things;
    } catch (error) {
        return new Error(error);
    }
}

processThings(5).then(function (things) {
    console.log(things);
}).catch(function (err) {
    console.log(err);
});