Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
Prior to Gecko 7.0 this method showed up as present, due to bug bug 9850, it always only returned null. The only workaround is to create a text node, CDATA section, attribute node value, etc. which has the value referred to by the entity, using Unicode escape sequences or fromCharCode() as necessary.