Polymorphism with React

In this article, we will create an example using Polymorphism in React.

Acceptance Criteria

Create a LinkButton that render an element button or a depending on the href prop
The LinkButton component has an optional prop called href
If the href is provided, the component should render an a tag. Otherwise, it should render a button tag

Solving the Problem without Polymorphism

import React from 'react'

export default function LinkButton({ href, children }) {
  if (href) {
    return <a href={href}>{children}</a>
  }

  return <button>{children}</button>
}

export default function App() {
  return (
    <>
      <h2>Navigation:</h2>
      <LinkButton>Button</LinkButton>
      <LinkButton href="/products">Link</LinkButton>
    </>
  )
}

It solves our problem, but imagine if we need to pass the rest of props to the component.

It will involve updating the button and the a, like the following example:

import React from 'react'

export default function LinkButton({ href, children, ...props }) {
  if (typeof href === 'string') {
    return (
      <a href={href} {...props}>
        {children}
      </a>
    )
  }

  return <button {...props}>{children}</button>
}

export default function App() {
  return (
    <>
      <h2>Navigation:</h2>
      <LinkButton>Button</LinkButton>
      <LinkButton href="/products">Link</LinkButton>
    </>
  )
}

And for every case you want to add props, you gonna need to maintain both cases, so much work, right?

Solving the Problem with Polymorphism

Let's create the same example using Polymorphism:

import React from 'react'

export default function LinkButton({ href, children, ...props }) {
  const Tag = typeof href === 'string' ? 'a' : 'button'

  return (
    <Tag href={href} {...props}>
      {children}
    </Tag>
  )
}

export default function App() {
  return (
    <>
      <h2>Navigation:</h2>
      <LinkButton>Button</LinkButton>
      <LinkButton href="/products">Link</LinkButton>
    </>
  )
}

You may be asking, and what about the href being passed to the button?

Since it will be undefined React will take control to avoid rendering this property to our HTML.

Wrapping Up

Keeping this approach in mind, you can create a component that handles the logic you want, and it will be easier to give maintenance.

I hope this tip was useful for you!