This test checks expressions with alternative lengths of appox. 2^31. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS regexp1.exec('') is null PASS regexp2.exec('') is null PASS regexp3.exec(s3) is null PASS function f() { /[^a$]{4294967295}/ } threw exception SyntaxError: Invalid regular expression: number too large in {} quantifier. PASS successfullyParsed is true TEST COMPLETE