Active Links

One way that Link is different from a is that it knows if the path it links to is active so you can style it differently.

Active Styles

Let's see how it looks with inline styles, add activeStyle to your Linkss.

// modules/App.js
<li><Link to="/about" activeStyle={{ color: 'red' }}>About</Link></li>
<li><Link to="/repos" activeStyle={{ color: 'red' }}>Repos</Link></li>

Now as you navigate, the active link is red.

Active Class Name

You can also use an active class name instead of inline-styles.

<li><Link to="/about" activeClassName="active">About</Link></li>
<li><Link to="/repos" activeClassName="active">Repos</Link></li>

We don't have a stylesheet on the page yet though. Lets add one--extra points if you can add a link tag from memory. Double extra points if you can leave the attributes unquoted, against your better judgement.

<link rel=stylesheet href=index.css />

And the css file:

.active {
  color: green;
}

You'll need to manually refresh the browser since Webpack isn't building our index.html.

Nav Link Wrappers

Most links in your site don't need to know they are active, usually just primary navigation links need to know. It's useful to wrap those so you don't have to remember what your activeClassName or activeStyle is everywhere.

Create a new file at modules/NavLink.js that looks like this:

// modules/NavLink.js
import React from 'react'
import { Link } from 'react-router'

export default React.createClass({
  render() {
    return <Link {...this.props} activeClassName="active"/>
  }
})

Now you can go change your links to NavLinks.

// App.js
import NavLink from './NavLink'

// ...

<li><NavLink to="/about">About</NavLink></li>
<li><NavLink to="/repos">Repos</NavLink></li>

Oh, how beautiful upon the renders is the composability of components.

Next: Params