React Holiday

Inject Components

Below is the first example on It shows the interplay of functions, JavaScript, JSX, and HTML that makes React unique.

let Greeting({ name }) { return <div>Hello {name}</div> }

It also demonstrates a big omission in the design of JSX.

JSX doesn’t have a syntax for rendering custom components with an alternate host element. Specially, this component will always render as a div — excluding it from inline use.

It’d be nice to tell React “render Greeting but as a span.”

There’s no first class JSX syntax for that. But React, JSX, and a bit of JS trickery make this possible in our own code. Use what we’ve learned about JS expressions to inject the desired component by passing it in as a prop.

<Greeting As="span" />

Of course custom components can be injected as well.

<Greeting as={MyFancyDiv} />

Here’s what this pattern looks like as a component declaration:

let Greeting({ As, name }) {
  return <As>Hello {name}</As>

Take it Home

There’s something kinda funny about this As prop we’ve made. That funny thing is because of a JSX heuristic we learned about earlier. Can you put your finger on it? Can you change it to make it more natural? Explore in this CodeSandbox.