首楞嚴義疏注經 1.102

1.102

阿難，此云歡喜。佛初出家，淨飯憂惱，聞子成道，王大忻然。復有斛飯，奏云生兒，舉國大喜，因立斯號。又彼端正，或語或默、行住坐臥、進止動轉，見者咸喜，故云歡喜。先受別請者，《涅槃經》說不受別請，乃不隨佛受別請耳，或因他事而非齋也。遑，假也。

Ānanda is translated here as "Joy." When the Buddha first went forth, Śuddhodana was anxious and distressed; hearing that his son had attained the Way, the king was greatly delighted. Moreover, Droṇodana reported that a son was born, and the whole country rejoiced greatly, so this name was established. Furthermore, he was handsome; whether speaking or silent, walking, standing, sitting, or lying down, in advancing, stopping, moving, or turning, all who saw him rejoiced; hence he is called "Joy." As for having previously accepted an individual invitation: the Nirvāṇa Sūtra states that one does not accept an individual invitation, which means merely not accompanying the Buddha to accept an individual invitation; or perhaps it was on account of other matters and was not a vegetarian meal. "Huang" means to happen by chance / have leisure for.