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ammario merged 1 commit into from
Nov 11, 2025
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docs: Add IIFE pattern for return statements in JS rules #90

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18 changes: 18 additions & 0 deletions docs/guide/rule-engines/javascript.md
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Expand Up @@ -62,6 +62,24 @@ r.host === 'facebook.com' ? {deny_message: 'Social media blocked'} : true
({allow: {max_tx_bytes: 1024}})
```

## Using Return Statements

JavaScript rules don't allow naked `return` statements. To use returns, wrap your code in an IIFE:

```javascript
(function() {
if (r.host === 'github.com') {
return true;
}

if (r.host.match(/facebook|twitter/)) {
return {deny_message: "Blocked"};
}

return false;
})();
```

## Common Patterns

### Domain Allowlisting
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