env-hoc (optimized for Next.js & After.js)

Provides an universal HOC (higher-order component) for React components and populates the component props and the getInitialProps args object with an env property, which gives access to cookies, language(s), userAgent and doNotTrack in a standardized way. If you are using Next.js / After.js you will get also access to the IP address and benefit heavily from the standardized API on server-side and client-side.

• Save time: Most important thing: short if-else-blocks, no formatting needed, no old-browser-carrying, etc.
• Standardized: Accept-Language && User-Agent && Cookie && DNT headers are parsed and available in the same format as in window. (same parsing libraries / functions && reformatting && backwards compatibility)
• Access to IP address: IP address is available client-side and there are checked 10+ properties to ensure you always get the best match. Supports enabling/disabling of proxy trusting.
• Fully tested: Tested for strange edge cases, missing HTTP headers or missing window properties.
• Some nice to have features:
  • Console.warns() while process.ENV.NODE_ENV === 'development', if server props !== client props
  • Possibility to only use props from the HTTP request

Feature requests for additional properties are welcomed

Install

You can install it directly from npm:

npm i env-hoc

or, if you are using yarn:

yarn add env-hoc

Usage

with decorators

Just import the package and add it as a decorator to every page where you want to have access to the env object.

import React from 'react';
import withEnv from 'env-hoc';

@withEnv
class Environment extends React.Component {
  //getInitialProps is a Next.js/After.js thing, just ignore it, if you aren't using one of them
  static getInitialProps(args) {
    console.log('args.env:', args.env);
  }

  render() {
    console.log('this.props:', this.props.env);
    return (
      <div>
        <h1>Environment</h1>
        <pre>userAgent: {this.props.env.userAgent}</pre>
        <pre>language: {this.props.env.language}</pre>
        <pre>languages: {this.props.env.languages.join(', ')}</pre>
        <pre>ipAddress: {this.props.env.ipAddress}</pre>
        <pre>cookies: {JSON.stringify(this.props.env.cookies)}</pre>
        <pre>doNotTrack: {this.props.env.doNotTrack ? 'true' : 'false'}</pre>
      </div>
    );
  }
}

export default Environment;

console output

/* CONSOLE OUTPUT:
args.env: { userAgent: 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36',
  language: 'de-DE',
  languages: [ 'de-DE', 'de', 'en-US', 'en', 'bs', 'hr' ],
  cookies: {},
  doNotTrack: true,
  ipAddress: '::1' }
this.props: { userAgent: 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36',
  language: 'de-DE',
  languages: [ 'de-DE', 'de', 'en-US', 'en', 'bs', 'hr' ],
  cookies: {},
  doNotTrack: true,
  ipAddress: '::1' }
*/

without decorators

Just import the package and wrap it around every page where you want to have access to the env object.

import React from 'react';
import withEnv from 'env-hoc';

class Environment extends React.Component {
  //getInitialProps is a Next.js/After.js thing, just ignore it, if you aren't using one of them
  static getInitialProps(args) {
    console.log('args.env:', args.env);
  }

  render() {
    console.log('this.props:', this.props.env);
    return (
      <div>
        <h1>Environment</h1>
        <pre>userAgent: {this.props.env.userAgent}</pre>
        <pre>language: {this.props.env.language}</pre>
        <pre>languages: {this.props.env.languages.join(', ')}</pre>
        <pre>ipAddress: {this.props.env.ipAddress}</pre>
        <pre>cookies: {JSON.stringify(this.props.env.cookies)}</pre>
        <pre>doNotTrack: {this.props.env.doNotTrack ? 'true' : 'false'}</pre>
      </div>
    );
  }
}

export default withEnv(Environment);

Example with options

//without decorator
withEnv({
  trustProxy: false,
})(Environment);

//with decorator
@withEnv({
  trustProxy: false,
})
class Environment extends React.Component {}

onetime configuration

You can also configure withEnv once in a file and then import it from there when needed.

//file: configuredWithEnv.js
export default withEnv({
  trustProxy: false,
});

//file: page.js
import configuredWithEnv from './configuredWithEnv';

//with decorator
@configuredWithEnv
export default class Environment extends React.Component {}

//without decorator
configuredWithEnv(class Environment extends React.Component {})

Configuration / Options

• trustProxy: (boolean) If true, then it trusts proxy HTTP headers.
• cookieParser: (object) Is beeing passed to the parse function of the cookie package.
• debug: (boolean) If true, then it console.warns() you about different client / server behaviour.
• useServerProps: (boolean/object) If true, only the props from server-rendering are used. You can also pass an object with keys matching the key from this.props.env and enable usage of server props only partially. For example:

withEnv({
    useServerProps: {
      cookies: true,
      languages: true,
    },
});

Default options

withEnv({
    trustProxy: true,
    cookieParser: {},
    debug: process.env.NODE_ENV === 'development',
    useServerProps: false,
});

Some hints

If you want to be a good programmer or support very old browsers, you should still check if a property is available, if some data isn't available, then it will be always for:

• all properties except cookies: null
• cookies: {}

So a short if () {} will do it mostly.