combineReducers

Redux Store 初始化与Reducer组合

最新推荐文章于 2022-10-14 14:40:32 发布

转载最新推荐文章于 2022-10-14 14:40:32 发布 · 74 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/CoderZX/p/10783818.html

本文详细解析了Redux中store初始化的过程，以及如何通过combineReducers函数来组合多个reducer，确保状态管理的一致性和模块化。同时，文章深入探讨了在组合过程中遇到的undefined状态的处理方式。

const reactInit = '@@react/Init'

const combineReducers  = (reducers) => {
    const finalReducers = {}
    for (let key in reducers) {
        const reducer = reducers[key]
        if (typeof reducer === 'undefined') {
            console.error(`reducer${key}的值是undefined`)
        }
        if (typeof reducer === 'function') {
            finalReducers[key] = reducer
        }
    }
    for (let key in  finalReducers) {
        const reducer = finalReducers[key]
        const state = reducer(undefined, reactInit)
        if (typeof state === 'undefined'){
            throw new Error(`reducer${key}的返回值为undefined`)
        }
    }
    return (state={}, action) => {
        for (let key in finalReducers) {
            const reducer = finalReducers[key]
            const newState = reducer(state[key], action)
            state[key] = newState
        }
        return state
    }
}