Check if browser prevents assignment to global undefined per ECMAScript 5.
Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; [email protected])
Checking...
Not supported
Unfortunately this browser does not support ES5 Immutable Undefined feature
Supported
Congratulation! This browser fully supports ES5 Immutable Undefined feature