src/third_party/mozjs-45/js/src/jit-test/tests/basic/bug683838.js

var rg = /(X(?:.(?!X))*?Y)|(Y(?:.(?!Y))*?Z)/g;
var str = "Y aaa X Match1 Y aaa Y Match2 Z";
assertEq(str.match(rg) + "", "X Match1 Y,Y Match2 Z");