* E4X was implemented in SpiderMonkey (Gecko's JavaScript engine) since version 1.6.0 until version 20, and is in Rhino (Mozilla's other JavaScript engine written in Java instead of C) since version 1.6R1.
* E4X реализован в SpiderMonkey (движок JavaScript на основе Gecko), начиная с версии 1.6.0, и в Rhino (еще один движок JavaScript от Mozilla, написанный на Java вместо Си), начиная с версии 1.6R1.