Joda Period Serializer Split

React preserves state by matching elements between renders by their position/order in the rendered tree and, more importantly, by the element’s key. Without stable keys, conditional rendering can change the element ordering/mapping so React may reuse component instances differently than intended. | When toggling hiddenFlag, the same number of MyComponent instances are shown, but their internal state (e.g., a counter) may be preserved for the wrong instance depending on whether components are conditionally rendered with an if/ternary or with inline logical rendering. How does React decide which component instance is the 'same' one? | Provide a stable key prop to the elements/components you want React to track across toggles. This forces React to correctly associate the stateful component instances with the same underlying logical item regardless of the conditional rendering structure.