Experiment: Mongoose like static & virtual methods

mongoose_core_v1.js

<script>
    const users = [{
        first: "Anwar",
        last: "Hussain",
        age: 27,
        profession: 'dev'
    }, {
        first: "Rafsan",
        last: "Hasemi",
        age: 25,
        profession: 'dev'
    }];

    // Creating constructor funciton
    function User(obj) {
        for (let key in obj) {
            this[key] = obj[key];
        }
    }

    // Creating static method to select first result
    User.findOne = function (obj) {
        // Think this as database query
        const result = users.filter(user => {
            let matched = false;
            for (let f_key in obj) {
                matched = user[f_key] === obj[f_key]
                if (!matched) return matched;
            }
            return matched;
        });

        if (!result.length) {
            return {
                error: 'No data found'
            }
        }
        return new User(result[0]);
    };

    // Creating static method to select all
    User.find = function (obj) {
        // Think this as database query
        const results = users.filter(user => {
            // return all data if no params passed
            if (obj == undefined || !Object.keys(obj).length) return true;

            let matched = false;
            for (let f_key in obj) {
                matched = user[f_key] === obj[f_key]
                if (!matched) return matched;
            }
            return matched;
        });

        if (!results.length) {
            return {
                error: 'No data found'
            }
        }

        return results.map((result) => {
            return new User(result);
        });
    };

    // Defining virtual property
    User.virtual = function (path) {
        return {
            get(callback) {
                Object.defineProperty(User.prototype, path, {
                    get: callback,
                    enumerable: true,
                    configurable: true
                });
                return this;
            },
            set(callback) {
                Object.defineProperty(User.prototype, path, {
                    set: callback,
                    enumerable: true,
                    configurable: true
                });
                return this;
            }
        }
    };

    // Setting how getter and setter should behave
    User
        .virtual('fullName')
        .get(function () {
            return `${this.first} ${this.last}`;
        })
        .set(function (name) {
            const [first, last] = name.split(' ');
            this.first = first;
            this.last = last;
        });

    // instance object
    const anwar = User.findOne({first: "Anwar"});
    const allUsers = User.find();

    console.log(anwar, allUsers);
</script>