React ref undefined. You could just simply set it to false.

React ref undefined For example, if you need to store an interval ID and retrieve it later, you can put it in a ref. You can access the current value of that ref through the ref. 当我们试图在其对应的DOM元素被渲染之前访问其current属性时，React的ref通常会返回undefined或者null。为了解决该问题，可以在useEffect钩子中访问ref，或者当事件触发时再访问ref。 In fact now that I think about it, the ref might even be redundant. (This is what makes it an “escape hatch” from React’s one-way data flow—more on that below!). Apr 7, 2024 · A React ref most commonly returns undefined or null when we try to access its current property before its corresponding DOM element is rendered. current is defined and then use what's within it – Treycos Changing a ref does not trigger a re-render. It’s like a secret pocket of your component that React doesn’t track. This value is intentionally mutable, meaning you can both read and write to it. To update the value inside the ref, you need to manually change its current property: Aug 1, 2022 · 正文从这开始~ 总览. Let's see an example: const ref = useRef<HTMLDivElement>(null); // some code ref. focus(); In the above code, we are using the non-null assertion operator (!) after ref. The ref will be undefined on the first rendering cycle, because your element does not exist yet. The second thing I notice is that your handleOutsideClick references a reactive value ( setShowSidebar ), which makes it a reactive function, and therefore should be wrapped in a useCallback hook and included in your useEffect dependency Aug 15, 2023 · This operator is used when you are sure that the expression preceding the operator is not null or undefined. current. To get around this, access the ref in the useEffect hook or when an event is triggered. You could just simply set it to false. This means refs are perfect for storing information that doesn’t affect the visual output of your component. current!. current property. Check if ref. wxri aiotn yhpdon acuho ykx ptokn pxigu jlfcg nzagkt fpfkt