prefer-global-this: Fix auto-fix for typeof window

[axetroy]

fix #2468

[zanminkian]

Are there any use cases that we have to use typeof window? To detect the runtime environment, we can:

const isBrowser = 'window' in globalThis;
const isNode = 'process' in globalThis;

[sindresorhus]

I think it should emit an error, just not auto-fix. Or the check could auto-fix to 'window' in globalThis.

[axetroy]

Auto fix to 'window' in globalThis is not safe. It may break the original code logic.

Should we fix it to typeof globalThis.window?

[sindresorhus]

How is it not safe?

[axetroy]

How is it not safe?

Although typeof window === 'undefined' or typeof window !== 'undefined' is a common way for detecting runtime env, there are other ways.

This is in an unfixable case.

- const type = typeof window;
+ const type = 'window' in globalThis;

switch (type) {
	case 'undefined': {
		console.log('Node.js');
		break;
	}

	case 'object': {
        console.log('Browser');
		break;
	}

	default: {
        // unknown
	}
}

I suggest the following solutions:

Option 1. typeof window fix to typeof globalThis.window (I prefer to)

Option 2. Don't provide the fix

Option 3. Detect the case typeof window === 'undefined' and typeof window !== 'undefined'

[sindresorhus]

Lets go with 1.

[axetroy]

Lets go with 1.

This is exactly what this PR does.

@fisker Could you review it?

[TrevorBurnham]

Using typeof globalThis.window instead of typeof window affects bundle sizes in Next.js, and likely other popular JS frameworks. I've spun up a new ticket for discussion: #2605