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Vue3响应式原理深度剖析：打造高性能状态管理架构

资深开发工程师 vue3

2025-08-01 0 891

Vue3响应式原理深度剖析：打造高性能状态管理架构

一、技术演进

Vue3响应式系统性能提升200%，内存占用减少40%

// Vue2 defineProperty
Object.defineProperty(obj, key, { get, set })

// Vue3 Proxy
new Proxy(obj, { get, set })

二、核心原理

1. 响应式基础实现

function reactive(obj) {
    return new Proxy(obj, {
        get(target, key, receiver) {
            track(target, key) // 依赖收集
            return Reflect.get(target, key, receiver)
        },
        set(target, key, value, receiver) {
            Reflect.set(target, key, value, receiver)
            trigger(target, key) // 触发更新
            return true
        }
    })
}

2. 依赖收集系统

let activeEffect
const targetMap = new WeakMap()

function track(target, key) {
    if (!activeEffect) return
    let depsMap = targetMap.get(target)
    if (!depsMap) {
        targetMap.set(target, (depsMap = new Map()))
    }
    let dep = depsMap.get(key)
    if (!dep) {
        depsMap.set(key, (dep = new Set()))
    }
    dep.add(activeEffect)
}

function trigger(target, key) {
    const depsMap = targetMap.get(target)
    if (!depsMap) return
    const effects = depsMap.get(key)
    effects && effects.forEach(effect => effect())
}

三、高级应用

1. 性能优化技巧

// 1. 浅层响应式
const shallowReactive = (obj) => new Proxy(obj, {
    get(target, key) {
        track(target, key)
        const res = target[key]
        return typeof res === 'object' ? res : reactive(res)
    }
    // ...set
})

// 2. 只读代理
function readonly(obj) {
    return new Proxy(obj, {
        get(target, key) {
            return Reflect.get(target, key)
        },
        set() {
            console.warn('只读对象不可修改')
            return true
        }
    })
}

2. 自定义ref实现

function customRef(factory) {
    let value
    const { get, set } = factory(
        () => {
            track(self, 'value')
            return value
        },
        (newVal) => {
            value = newVal
            trigger(self, 'value')
        }
    )
    const self = {
        get value() { return get() },
        set value(v) { set(v) }
    }
    return self
}

// 使用示例
const debouncedRef = customRef((track, trigger) => {
    let timer
    return {
        get() {
            track()
            return value
        },
        set(newVal) {
            clearTimeout(timer)
            timer = setTimeout(() => {
                value = newVal
                trigger()
            }, 500)
        }
    }
})

四、完整案例

简易状态管理系统

class Store {
    constructor(state) {
        this._state = reactive(state)
        this._mutations = {}
        this._actions = {}
    }
    
    get state() {
        return readonly(this._state)
    }
    
    commit(type, payload) {
        this._mutations[type]?.(this._state, payload)
    }
    
    dispatch(type, payload) {
        return this._actions[type]?.(this, payload)
    }
    
    mutation(type, handler) {
        this._mutations[type] = handler
    }
    
    action(type, handler) {
        this._actions[type] = handler
    }
}

// 使用示例
const store = new Store({ count: 0 })
store.mutation('increment', (state) => state.count++)
store.action('asyncIncrement', ({ commit }) => {
    setTimeout(() => commit('increment'), 1000)
})

function checkVueVersion() {
alert(‘请确保使用Vue3.0+版本运行示例代码’);
}