add note that the void operator doesn't work on arrow function iifes (m…

…dn#35857)

files/en-us/web/javascript/reference/operators/void/index.md

@@ -74,6 +74,12 @@ This is a bit longer than wrapping the function expression in parentheses, which
 })();
 ```
 
+Note that this trick only applies to IIFEs defined with the `function` keyword. Attempting to use the `void` operator to avoid parentheses for an arrow function results in a syntax error. Arrow function expressions always require parentheses around them when being called.
+
+```js example-bad
+void () => { console.log("iife!"); }(); // SyntaxError: Malformed arrow function parameter list
+```
+
 ### JavaScript URIs
 
 When a browser follows a [`javascript:` URI](/en-US/docs/Web/URI/Schemes/javascript), it evaluates the code in the URI