如何在 React useRef 中设置引用

Question

I'm trying to play a gsap animation on component did mount in a Gatsby site but my refs aren't being applied.

const PricingList = ({ classes }) => {
    let pricingCard = useRef([]);

    useEffect(() => {
        console.log('start Animation', pricingCard.current);
        TweenMax.staggerFrom(pricingCard.current, 0.4, { opacity: 0, y: 100 }, 0.5);
    }, []);

    return (
        <StaticQuery
            query={graphql`
                {
                    Prices: contentfulConfig {
                        pricing {
                            priceBand {
                                title
                                price
                            }
                            priceBand2 {
                                price
                                title
                            }
                            priceBand3 {
                                price
                                title
                            }
                        }
                    }
                }
            `}
            render={(data) => (
                <Fragment>
                    <div className={classes.Container}>
                        <PricingItem
                            ref={(el) => {
                                pricingCard.current[0] = el;
                            }}
                        />
                        <PricingItem
                            ref={(el) => {
                                pricingCard.current[1] = el;
                            }}
                        />
                        <PricingItem
                            ref={(el) => {
                                pricingCard.current[2] = el;
                            }}
                        />
                    </div>
                </Fragment>
            )}
        />
    );
};

I have tried -

pricingCard.current.push(el);

without any luck, I just get an empty array in console.

I have also tried -

    useEffect(() => {
        console.log('start Animation', pricingCard.current);
        TweenMax.staggerFrom(pricingCard.current, 0.4, { opacity: 0, y: 100 }, 0.5);
    }, [pricingCard]);

Thinking it might need to wait to be updated after the component mounted, but no luck.

Any help would be appreciated.

Thanks in advance.

Answer 1

For animation you might want to use useLayoutEffect instead of useEffect .

Is it going to be always 3 PricingItem s? In this case you can create 3 separate refs for each ( const pricingItem1 = useRef(null) ) and in render <PricingItem ref={pricingItem1} /> .

Also can you confirm that the function from the render prop has been called?