Function useState

mini-react/src/mini-react.js:207–239

(initialState)

    }
    
    function useState(initialState) {
        const currentFiber = wipFiber;

        const oldHook = wipFiber.alternate?.stateHooks[stateHookIndex];

        const stateHook = {
          state: oldHook ? oldHook.state : initialState,
          queue: oldHook ? oldHook.queue : [],
        };
        
        stateHook.queue.forEach((action) => {
          stateHook.state = action(stateHook.state);
        });

        stateHook.queue = [];

        stateHookIndex++;
        wipFiber.stateHooks.push(stateHook);

        function setState(action) {
          const isFunction = typeof action === "function";

          stateHook.queue.push(isFunction ? action : () => action);

          wipRoot = {
            ...currentFiber,
            alternate: currentFiber,
          };
          nextUnitOfWork = wipRoot;
        }
      
        return [stateHook.state, setState];
    }
    
    function useEffect(callback, deps) {
      const effectHook = {