Link with activeClassName

[sedubois]

Similar to react-router's Link, it would be nice to be able to customize CSS when a link is active, e.g with an activeClassName property.

[nkzawa]

duplicate of https://github.com/zeit/next.js/issues/127

[sedubois]

This isn't a duplicate, right now there is no way to style a link specifically when a route is active. React-router provides this in 147 + 233 LOCs. Although it's possible to take shortcuts thankfully 😄

[nkzawa]

ohhh, sorry!

It might be nice to have the activeClassName property, but you can manually detect if a route is active and set any class to the Link anyway ?

[luisrudge]

this would be super nice to have indeed!

[sedubois]

@nkzawa AFAIK detecting that requires 2 things:

• passing the router URL all the way from the page root down to the component having the Link. Either it pollutes all the intermediate component signatures (including propTypes) or need to set up a contextType.
• comparing the router URL with the Link's href. As shown in react-router above (isActive method), it's not trivial.

Would be great to have Next take care of this instead of every user reimplementing it.

[viankakrisna]

Or maybe a withLocation HOC. And wrap Link with that HOC. Then import that instead of next/link

[arunoda]

One way to support is provide a way to get current state of the router using next/router. But it's not working on the Server.

So, what ever thing we need to done inside a componentDidMount hook. @nkzawa If we allow next/router on the server (Just for SSR) this would be great. Is there's any chance we could support it?

[timneutkens]

I'm thinking it might be implemented using componentDidMount since it's only executed client side. I'm not sure if it's executed every route change though.

Edit: seems like Arunoda thought the same thing above 👍

[ghost]

I think this would be a very good addition to the Links, I wonder if Zeit did it on zeit.co the way @mallendeo described

[hieuhlc]

Hey guys is this feature currently still developing?

[arunoda]

I think this is pretty easy to do without core support.

[hieuhlc]

I tried adding active classname in componentDidMount but it doesn't seem right. At first render active classname does not occur.

[mtford90]

@arunoda do you have a good example of how to implement this given that it's pretty easy?

I use query parameters within my app and I've had to do some fairly ugly stuff to get the active class names to render the same on both client & server. Core support would be much nicer.

[andrewmclagan]

The main issue is its not only <Link /> that needs this functionality. other components such as custom buttons and such also need to know if they have an active route... I really really think this should be a utility attached to Router

<Component isActive={Router.isActive('/path/to/check')} />

The idea of having to pass down the pathname from the top level Page component is a code smell. What if your component is nested 10 deep..? Dont we want to abstract SSR quirks from the dev, is that not the point of this framework?

<Link /> could attach a active class automatically?

import Router from 'next/router';

const isActiveRoute = route => {
  if (typeof window !== 'undefined' && window.document && window.document.createElement) {
    return Router.pathname === route;
  }
  // Okay, now how to get the current route on the server?
  // assuming we would need to access the `req` object through a middleware.
  // return req && req.url;
}

export default isActiveRoute;

Work around

We currently use react context to get around this spaghetti nightmare.

// Page.js
import React from 'react';
import PropTypes from 'prop-types';
import Button from '../components/Button';

export default class Page extends React.Component {

  static getInitialProps ({ pathname, req }) {
    return { pathname: req && req.url || pathname  };  
  }

  static childContextTypes = {
    pathname: PropTypes.string,
  }  

  getChildContext() {
    return { pathname: this.props.pathname };
  }    

  render () {

    return (
      <div>
        <div>
          <div>
            <div>
              <Button />
            </div>
          </div>
        </div>
      </div>
    )
  }
}

And the deeply nested component that needs knowledge

import React from 'react';
import PropTypes from 'prop-types';
import classNames from 'classnames';

export default class Button extends React.Component {

  static contextTypes = {
    pathname: PropTypes.string,
  }  

  render() {

    const visible = this.context.pathname !== '/';

    return (
      <button className={classNames('btn-search', { visible })}>
        My Button
      </button>      
    );
  }
}

Not ideal...

[steida]

@andrewmclagan It's not so easy.

This usage can't handle URL change:

<Component isActive={Router.isActive('/path/to/check')} />

URL changes, so whenever we need to handle URL change, we need higher order component to enforce rerender. Something like injectUrl(PageHeader)

[andrewmclagan]

@steida yeah i figured that would be the case.

What about a wrapping component that uses context (as in my example above) that passes a className or isActive property to the child component?

I guess the main issue is keeping a codebase DRY is hard having to pass context down from every single page to do such a simple thing as active link. I really believe its a responsibility of the framework?

[ghost]

fwiw I still think this should be built into next/link

[steida]

I think this is pretty easy to do without core support.

Do you have a good example of how to implement this given that it's pretty easy?

Use the title, Luke.

That's how I am doing it in Este.

// @flow
import A from './a';
import Box from './box';

const HeaderA = ({ children, href, title }) => (
  <A
    backgroundColor="primary"
    bold
    color="white"
    href={href}
    isActive={title === children}
    paddingHorizontal={0.5}
    paddingVertical={0.5}
    prefetch
  >
    {children}
  </A>
);

type PageHeaderProps = { title: string };

const PageHeader = ({ title }: PageHeaderProps) => (
  <Box
    backgroundColor="primary"
    flexDirection="row"
    flexWrap="wrap"
    marginVertical={0.5}
    paddingHorizontal={0.5}
  >
    <HeaderA href="/" title={title}>Home</HeaderA>
    <HeaderA href="/about" title={title}>About</HeaderA>
  </Box>
);

export default PageHeader;

I think this is the right pattern. Not all links in an app must have an active state. Route change watchers are hard to implement and break clear data flow.

UPDATE: Maybe the example isn't obvious enough. I meant that we have to generate page titles anyway, and we can use generated page titles to match active route without sophisticated pathname parsing nor route change watching.

[ayazhussein]

The solution I found (might not be the best one) is to use path-to-regexp classnames packages and I made a util function that checks if the route is active by passing the props to my nav component...

// ./lib/activePath.js
import pathToRegexp from "path-to-regexp";

export function activePath(currentPath, path , options) {
  const regexPath = pathToRegexp(path, options);

  const result = regexPath.exec(currentPath);
  return result;
}

// ./component/Header.js
import React, { Component } from 'react';
import Link from "next/link";
import { activePath } from "../lib/activePath";
import classnames from "classnames";
class Header extends Component {
  render() {
    const { url } = this.props;
    const { pathname } = url;
    return (
      <header>
        <nav className="navbar navbar-toggleable-md navbar-light bg-faded">
          <button className="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavAltMarkup" aria-controls="navbarNavAltMarkup" aria-expanded="false" aria-label="Toggle navigation">
            <span className="navbar-toggler-icon" />
          </button>
          <a className="navbar-brand">Title</a>
          <div className="collapse navbar-collapse" id="navbarNavAltMarkup">
            <div className="navbar-nav">
              <Link href="/">
                <a className={classnames("nav-item nav-link", { active: activePath(pathname, "/", { strict: true }) })}>Home <span className="sr-only">(current)</span></a>
              </Link>
              <Link href="/about">
                <a className={classnames("nav-item nav-link", { active: activePath(pathname, "/about", { strict: true }) })} >About</a>
              </Link>
              <Link href="/about/us">
                <a className={classnames("nav-item nav-link", { active: activePath(pathname, "/about/us", { strict: true }) })} >About US</a>
              </Link>
              <Link href="/contact">
                <a className={classnames("nav-item nav-link", { active: activePath(pathname, "/contact", { strict: true }) })} >Contact</a>
              </Link>
            </div>
          </div>
        </nav>
      </header >
    );
  }
}

export default Header;

the header is in my layout component so I have to pass the props to it on every page so that the header would have access to url props...

I'm open to other solutions too :D

[arunoda]

Guys, we are going to implement a new API to make these kind of functionalities simple. See: https://github.com/zeit/next.js/issues/2032

[andrewmclagan]

@arunoda Thanks I feel this was always going to be the right direction. We basically took the HOC route ourselves.

[postor]

hi guys, I made it using next-routes which makes one route define for both server side and client side, example here https://hello-next-lhafgwnfxp.now.sh/ and code here https://github.com/postor/nextjs-boilerplate

[timneutkens]

We'll merge the withRoute HOC after v3 has been released. Then this will be possible. https://github.com/zeit/next.js/pull/2352