Function setState

zustand-test/src/myZustand.js:7–22

(partial, replace)

    const listeners = new Set();
  
    const setState = (partial, replace) => {
      const nextState = typeof partial === 'function' ? partial(state) : partial

      if (!Object.is(nextState, state)) {
        const previousState = state;

        if(!replace) {
            state = (typeof nextState !== 'object' || nextState === null)
                ? nextState
                : Object.assign({}, state, nextState);
        } else {
            state = nextState;
        }
        listeners.forEach((listener) => listener(state, previousState));
      }
    }
  
    const getState = () => state;