ReactJS - Unknown prop `activeClassName` on <a> tag. Remove this prop from the element

Question

I am using react 15.4.2 and react-router4.0.0 and This project was bootstrapped with Create React App .

Here is my Code.

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import {BrowserRouter as Router,Route,Link} from 'react-router-dom'


 const AboutPage = () => {
 return(
    <section>
        <h2>This is About page</h2>
        <Link activeClassName="active" to="/about/nestedone">Nestedone</Link>
        {' '}
        <Link activeClassName="active" to="/about/nestedtwo">Nested two</Link>
    </section>
)
}

const HomePage = () => {
return(
    <section>
        <h2>This is Home page</h2>
        <Link to="/about">About</Link>
    </section>
)
}

const NestedOne = () => {
return (
    <section>
        <h2>Nested page 1</h2>
    </section>
)
}


const NestedTwo = () => {
return (
    <section>
        <h2>Nested page 2</h2>
    </section>
)
}


 ReactDOM.render(
 <Router> 
  <section>
    <Route exact path="/" component={HomePage} />
    <Route path="/about" component={AboutPage} />
    <Route path="/about/nestedone" component={NestedOne} />
    <Route path="/about/nestedtwo" component={NestedTwo} />
 </section>
 </Router>,
  document.getElementById('root')
);

When I browse /about , I am getting this error:

"Warning: Unknown prop activeClassName on tag. Remove this prop from the element.

What am I doing wrong here?

Thanks!

Answer 1

The activeClassName property is not a property of Link but of NavLink.

So, just change your code to use NavLink instead of Link:

const AboutPage = () => {
 return(
    <section>
        <h2>This is About page</h2>
        <NavLink activeClassName="active" to="/about/nestedone">Nestedone</NavLink>
        {' '}
        <NavLink activeClassName="active" to="/about/nestedtwo">Nested two</NavLink>
    </section>
)

Remember to import the NavLink from the react-router-dom :

import {  NavLink } from 'react-router-dom'

Answer 2

From v6 onwards of react-router replace activeClassName with className and use navData.isActive to toggle style.

---

Old way:

<NavLink to="/home" activeClassName="active-style">Home</NavLink>

v6 onwards:

<NavLink to="/home" className={(navData) => (navData.isActive ? "active-style" : 'none')}>Home</NavLink>

or you can also destructure isActive from navData :

 <NavLink to="/home" className={({isActive}) => (isActive ? "active-style" : 'none')}>Home</NavLink>

Answer 3

In React Router v6 activeClassName has been changed to just className where a prop isActive can be used to manipulate the styling.

For more info
https://reactrouter.com/docs/en/v6/upgrading/v5#remove-activeclassname-and-activestyle-props-from-navlink-

const AboutPage = () => {
    return(
        <section>
        <h2>This is About page</h2>
        <NavLink className={({ isActive }) => isActive? "active": ''} to="/about/nestedone">Nestedone</NavLink>
        {' '}
        <NavLink className={({ isActive }) => isActive? "active": ''} to="/about/nestedtwo">Nested two</NavLink>
        </section>
    )
}

Answer 4

activeClassName is not a property of Link but of NavLink .

Since react-router v4 beta8 , the property is active by default. Verify which version is installed in your node modules folder

Answer 5

My issue was that I was using reactstrap and importing their NavLink element which does NOT have the attribute activeClassName . Make sure you import NavLink from the react-router library like this:

import { NavLink } from 'react-router-dom'