React changing useState not rendering component when using map to generate elements-CodePudding

here is my case, i'm loading SVG file and rendering it to the screen. i would like to change to colors of the svg file. (svg file contains 500 objects)

all works good, and seems like the state has been changed but the component are not been rendered. i think this is because i'm using the map in order to generate the elements - here is my code:

const Sim = () => {

    const [elements, setElements] = useState([]);

    const loadSVG = (e) => {
       ...
       ...
            newElements = newElements.map(x=> ({
                data: x,
                color: '#0a22a0'
            }))

            setElements(newElements)
        };
    }

    const rndColors = () => {

        elements.forEach(x=> {
            x.color = "#"   Math.floor(Math.random()*16777215).toString(16);
        })

        setElements(elements)
        console.log(elements)
        
    }

    return (
        <div>
            <Button style={{marginBottom: 10, maxHeight: 20}} size="small" variant="outlined" onClick={rndColors}>RND Colors</Button>
            <svg
                viewBox="0 0 2000 2000"
                version="1.1"
                x="0px"
                y="0px"
                style={{maxHeight:700}}
            >
            {elements.map((x,i) =>
                <SVGElement
                    data={x.data}
                    index={i}
                    color={x.color}
                />)
            }
            </svg>

        </div>
    )
}

i could clearly see in the logs the colors are changed, but the actual svg color is not changed (only after i change something in the code the page refreshed - i can see the new colors)

How can i make sure that once i click the button all of the colors of the svg will be changed? something is not triggering here the render cycle of the elements.. what do i missing here?

CodePudding user response：

elements.forEach((x) => {
  x.color = "#"   Math.floor(Math.random() * 16777215).toString(16);
});

setElements(elements);

You are mutating the state above, you should always update state in immutable way. You can rewrite above code to:

setElements(
  elements.map((x) => ({
    ...x,
    color: "#"   Math.floor(Math.random() * 16777215).toString(16),
  }))
);