NodeJS Express response formatter

Reponse.js

module.exports = class Response {

    constructor(response) {
        this.code = response.statusCode;
        this.date = new Date();

        this.error = [];
        this.data = {};

        return this;
    }

    /**
     * Set the message which will be displayed in the response
     * @param {String} message 
     * @returns Response
     */
    setMessage(message) {
        this.message = message;
        return this;
    }

    /**
     * Adds an error to the response
     * @param {String} error
     * @param {String} message 
     * @default code = ''
     * @returns Response
     */
    addError(error, message = -1) {
        this.error.push({code: error, id: message});

        return this;
    }

    /**
     * Adds data to the response
     * @param {Object} key 
     * @param {Object} value 
     * @returns Response
     */
    addData(key, value) {
        this.data[key] = value;
        return this;
    }

    /**
     * Returns the response as an json object
     * @returns Object
     */
    init() {
        return ({
            code: this.code,
            date: this.date,
            message: this.message || '',
            data: this.data,
            error: this.error,
        });
    }

}