Reusable Node Code Modules, Part 12 - Data Transformation and Formatting

Optimizing Data Flow: Building Reusable Data Transformation and Formatting Modules

Data transformation and formatting are crucial for ensuring that data is consistent, clean, and suitable for further processing or presentation. Implementing reusable data transformation and formatting modules ensures consistency and efficiency across projects. This guide covers how to structure reusable data transformation and formatting modules in Node.js using Express, manage data transformation efficiently, and integrate common libraries.

Common Libraries and Tools

1. Lodash

Lodash is a utility library delivering consistency, modularity, and performance

Key Features

• Utility Functions: Provides a wide range of utility functions for common programming tasks

• Performance: Optimized for performance with low overhead

• Modular: Supports individual function imports to reduce bundle size

• Consistency: Ensures consistent behavior across different environments

2. Moment.js (and alternatives)

Moment.js is a popular library for parsing, validating, manipulating, and formatting dates. Alternatives include Day.js and date-fns

Key Features

• Date Manipulation: Comprehensive date manipulation capabilities

• Formatting: Extensive date formatting options

• Locales: Supports multiple locales

• Plugins: Rich ecosystem of plugins for additional functionality

3. Numeral.js

Numeral.js is a library for formatting and manipulating numbers

Key Features

• Number Formatting: Supports various number formats including currency, percentages, and custom formats

• Locale Support: Provides localization for number formats

• Parsing: Parses numbers from formatted strings

• Lightweight: Minimal footprint and easy to use

4. Joi

Joi is a powerful schema description language and data validator for JavaScript objects

Key Features

• Validation: Validates JavaScript objects based on schema definitions

• Transformation: Supports transformation of data during validation

• Custom Rules: Allows creation of custom validation rules

• Integration: Easily integrates with Express and other frameworks

Comparison

• Lodash: Best for general-purpose utility functions with a focus on performance and modularity.

• Moment.js: Ideal for comprehensive date manipulation and formatting, with Day.js and date-fns as lightweight alternatives.

• Numeral.js: Suitable for flexible and localized number formatting and manipulation.

• Joi: Best for schema-based data validation and transformation with support for custom rules.

Examples and Wrapper Class

Example 1: Lodash

Setup:

$ npm install lodash

Configuration:

import _ from 'lodash';

const transformData = (data) => {
  return _.map(data, item => _.pick(item, ['id', 'name', 'value']));
};

export default transformData;

Wrapper Class:

class DataTransformer {
  constructor() {
    this._ = _;
  }

  transform(data) {
    return this._.map(data, item => this._.pick(item, ['id', 'name', 'value']));
  }
}

export default new DataTransformer();

Example 2: Moment.js

Setup:

$ npm install moment

Configuration:

import moment from 'moment';

const formatDate = (date, format) => {
  return moment(date).format(format);
};

export default formatDate;

Wrapper Class:

class DateFormatter {
  constructor() {
    this.moment = moment;
  }

  format(date, format) {
    return this.moment(date).format(format);
  }

  parse(dateString, format) {
    return this.moment(dateString, format).toDate();
  }
}

export default new DateFormatter();

Example 3: Numeral.js

Setup:

$ npm install numeral

Configuration:

import numeral from 'numeral';

const formatNumber = (number, format) => {
  return numeral(number).format(format);
};

export default formatNumber;

Wrapper Class:

class NumberFormatter {
  constructor() {
    this.numeral = numeral;
  }

  format(number, format) {
    return this.numeral(number).format(format);
  }

  parse(numberString) {
    return this.numeral(numberString).value();
  }
}

export default new NumberFormatter();

Example 4: Joi

Setup:

$ npm install joi

Configuration:

import Joi from 'joi';

const schema = Joi.object({
  id: Joi.number().integer().required(),
  name: Joi.string().required(),
  value: Joi.number().required()
});

const validateData = (data) => {
  const { error, value } = schema.validate(data);
  if (error) {
    throw new Error(`Validation error: ${error.message}`);
  }
  return value;
};

export default validateData;

Wrapper Class:

class DataValidator {
  constructor() {
    this.schema = Joi.object({
      id: Joi.number().integer().required(),
      name: Joi.string().required(),
      value: Joi.number().required()
    });
  }

  validate(data) {
    const { error, value } = this.schema.validate(data);
    if (error) {
      throw new Error(`Validation error: ${error.message}`);
    }
    return value;
  }

  extend(schemaExtension) {
    this.schema = this.schema.keys(schemaExtension);
  }
}

export default new DataValidator();