If/else

templ uses standard Go if/else statements which can be used to conditionally render components and elements.

component.templ

templ login(isLoggedIn bool) {
  if isLoggedIn {
    <div>Welcome back!</div>
  } else {
    <input name="login" type="button" value="Log in"/>
  }
}

main.go

package main

import (
	"context"
	"os"
)

func main() {
	login(true).Render(context.Background(), os.Stdout)
}

Output

<div>
 Welcome back!
</div>