// without SSR (server-side rendering) — React example
import React from 'react'
import detectBrowserLanguage from 'detect-browser-language'

export default () =>
  <h1>{detectBrowserLanguage()}</h1>

// with SSR (server-side rendering) — React example
import React, { Component } from 'react'

export default class Page Component {
  componentDidMount() {
    const detectBrowserLanguage = require('detect-browser-language')
    this.setState({ userLanguage: detectBrowserLanguage() })
  }

  render() {
    const { userLanguage } = this.state

    return <h1>{userLanguage}</h1>
  }
}