IIFE not checkt for semicolon at the start?

[borisdiakur]

https://github.com/feross/standard/blob/master/RULES.md#semicolons suggests the following:

// ✓ ok
;(function () {
  window.alert('ok')
}())

// ✗ avoid
(function () {
  window.alert('ok')
}())

However, when I navigate to http://standardjs.com/demo.html and paste the following code, the linter tells me it’s fine:

(function () {
  window.alert('ok')
})()

I’m new to the no semicolons style, so now I’m confused. Either the documentation or the linter is wrong.

[Flet]

If there is no code above the IIFE, it will work OK.

It becomes more clear when adding a line at the top:
http://standardjs.com/demo.html?gist=f925d40642900c782d2b9d9e18731ece

[borisdiakur]

Here is an example with code above. It’s still ok:

if (typeof foo !== 'undefined') {
  throw new Error('foo is already defined!')
}

(function () {
  window.alert('ok')
}())

http://standardjs.com/demo.html?gist=7382351fed23caf08381c01669b0900d

[Flet]

Indeed, this one is a funny edge case :)

Somewhat related: #70

[Flet]

There is not a specific rule that enforces semicolons before IIFEs, but other rules will catch problems if they arise (like func-call-spacing).

Never start a line with (, [, or `. This is the only gotcha with omitting semicolons, and standard protects you from this potential issue.

The guideline above will ensure code always works, even if there is a special edge case where its not required (like a preceding if block).

If this is uncomfortable, there is always semistandard :)

[borisdiakur]

As long as standard catches all problems related to missing semicolons I feel comfortable.

There is not a specific rule that enforces semicolons before IIFEs, but other rules will catch problems if they arise (like func-call-spacing).

Maybe that should be noted in the RULES.md?

[feross]

standard catches all problems related to missing semicolons. 👍