methods: {     setCameraPostion: (()=>{        let _eye = new Vector3();        let eyeDirection = new Vector3();        let target = new Vector3();        let distance, newDistance;        return function setCameraPostion(args) {             _eye.copy(args.pos).sub(target);             eyeDirection.copy(_eye).normalize();             distance = _eye.length();             newDistance = ...(有點長，略過);             eyeDirection.setLength(newDistance).add(target);            return eyeDirection;         }     })(), }以上寫法是可以執行的，我想問得是這種寫法是否可??？需不需要優化？個人感覺這種輔助變量寫在data里很別扭...強迫癥了快但缺點是無法使用this——不知道怎么用謝謝