michael@0: var re = /abc(WHOO!)?def/y;
michael@0: var input = 'abcdefabcdefabcdef';
michael@0: var count = 0;
michael@0: while ((match = re.exec(input)) !== null) {
michael@0:     print(count++);
michael@0:     assertEq(match[0], 'abcdef');
michael@0:     assertEq(match[1], undefined);
michael@0: }