Discussion on: ELI5: Why use a function declaration, expression, or an IIFE in JavaScript?

View post

Replies for: Yes, you are correct that an IIFE creates its own scope. As a consequence of that, any variable declared inside an IIFE is only visible to its scop...

The one place where IIFEs can still be useful is surprisingly async/await in Node.

You can't use await outside of async so you end up doing something like:

(async () => {
  try {
    await something()
  } catch(e) {
    console.error(e.stack)
    process.exit(1)
  }
})()

That's unless you have top-level await support in your environment (which Node doesn't but the esm package can be configured to provide or if you transpile)

Basti Ortiz • Feb 25 '19

Oh, yeah. How could I forget about that?

Also, just a side note, I just realized now that top-level await is essentially a glorified way of writing top-level synchronous code. That's kind of strange... 🤔

Ryan Johnson • Jan 15 '20

You could argue that the following syntax is subjectively easier to grok, because it's explicit about the definition and execution of the async function main. However, there's no technical advantage of one syntax vs the other.

async function main () {
  try {
    await something()
  } catch (e) {
    console.error(e.stack)
    process.exit(1)
  }
}

main()