Function setState

mini-react/src/mini-react.js:226–236

(action)

        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];
    }