Run results for: typeof vs undefined

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:74.0) Gecko/20100101 Firefox/74.0

Browser: Firefox 74

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 4 years ago

Script Preparation code:

var x;
var und = 'unde';
und += 'fined'

Tests: