Fix trailing whitespace in Astro components

• A closed issue on GitHub appears to still be occurring
• Forcing your code onto a single line is a workaround

When your Astro code is formatted onto multiple lines, the resulting markup from the Astro compiler includes a whitespace. This is noticeable when you have a list of links that are underlined:

<a>
  Link 1
</a>
<a>
  Link 2
</a>

Result: Link 1    Link 2

But if the markup is on a single line, then the issue goes away:

<a>Link 1</a>
<a>Link 2</a>

Result: Link 1   Link 2

I have faked the output for this article, but you can see a live reproduction of this behavior on StackBlitz.

To workaround this issue, you need force your markup onto a single line. Let’s look at a real-world example element with multiple attributes. Your code formatter will spread it over multiple lines:

{items.map(item => {
  return (
    <a
      aria-current={Astro.url.pathname === item.url ? "page" : null}
      href={item.url}
    >
      {item.label}
    </a>
  )
})

To force this code onto a single line, we need to refactor. Create variables to represent attributes and children with short names, and then pass them to the element:

{items.map(item => {
  const a = {
    'aria-current': Astro.url.pathname === item.url ? "page" : null,
    href: item.url
  }
  const c = item.label
  return <a {...a}>{c}</a>
})

This code is objectively worse (and might create a TypeScript warning that you need to ignore), but it will fix the whitespace issue. Hopefully the Astro team can fix the issue in the compiler and make this workaround unnecessary.