next.js/test/integration/production/pages/counter.js

import Link from 'next/link'
import { Component } from 'react'
import Router from 'next/router'

let counter = 0

export default class extends Component {
  increase () {
    counter++
    this.forceUpdate()
  }

  visitQueryStringPage () {
    const href = { pathname: '/nav/querystring', query: { id: 10 } }
    const as = { pathname: '/nav/querystring/10', hash: '10' }
    Router.push(href, as)
  }

  render () {
    return (
      <div id='counter-page'>
        <Link href='/no-such-page'><a id='no-such-page'>No Such Page</a></Link>
        <p>This is the home.</p>
        <div id='counter'>
          Counter: {counter}
        </div>
        <button id='increase' onClick={() => this.increase()}>Increase</button>
      </div>
    )
  }
}