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js实现v

2026-03-02 04:50:46JavaScript

以下是JavaScript实现Vue.js核心功能的简化示例，涵盖数据绑定、指令和虚拟DOM的基本概念：

数据绑定

通过Object.defineProperty实现响应式数据：

class Observer {
  constructor(data) {
    this.observe(data)
  }

  observe(data) {
    if (!data || typeof data !== 'object') return
    Object.keys(data).forEach(key => {
      this.defineReactive(data, key, data[key])
    })
  }

  defineReactive(obj, key, val) {
    const dep = new Dep()
    this.observe(val)
    Object.defineProperty(obj, key, {
      get() {
        Dep.target && dep.addSub(Dep.target)
        return val
      },
      set(newVal) {
        if (newVal === val) return
        val = newVal
        dep.notify()
      }
    })
  }
}

class Dep {
  constructor() {
    this.subs = []
  }

  addSub(sub) {
    this.subs.push(sub)
  }

  notify() {
    this.subs.forEach(sub => sub.update())
  }
}

指令解析

实现v-model双向绑定：

class Compiler {
  constructor(el, vm) {
    this.vm = vm
    this.el = document.querySelector(el)
    this.compile(this.el)
  }

  compile(node) {
    Array.from(node.childNodes).forEach(child => {
      if (this.isElementNode(child)) {
        this.compileElement(child)
      } else if (this.isTextNode(child)) {
        this.compileText(child)
      }
      if (child.childNodes && child.childNodes.length) {
        this.compile(child)
      }
    })
  }

  compileElement(node) {
    Array.from(node.attributes).forEach(attr => {
      if (this.isDirective(attr.name)) {
        const dir = attr.name.substring(2)
        this[dir] && this[dir](node, attr.value)
      }
    })
  }

  model(node, exp) {
    node.value = this.vm[exp]
    new Watcher(this.vm, exp, val => {
      node.value = val
    })
    node.addEventListener('input', e => {
      this.vm[exp] = e.target.value
    })
  }
}

虚拟DOM简化实现

class VNode {
  constructor(tag, data, children, text) {
    this.tag = tag
    this.data = data
    this.children = children
    this.text = text
  }
}

function createElement(tag, data, children) {
  return new VNode(tag, data, children)
}

function patch(oldVnode, vnode) {
  if (!oldVnode) {
    return createElm(vnode)
  }
  const isRealElement = oldVnode.nodeType !== undefined
  if (isRealElement) {
    const parent = oldVnode.parentNode
    const elm = createElm(vnode)
    parent.insertBefore(elm, oldVnode)
    parent.removeChild(oldVnode)
    return elm
  }
}

function createElm(vnode) {
  if (vnode.tag) {
    vnode.elm = document.createElement(vnode.tag)
    if (vnode.children) {
      vnode.children.forEach(child => {
        vnode.elm.appendChild(createElm(child))
      })
    }
  } else {
    vnode.elm = document.createTextNode(vnode.text)
  }
  return vnode.elm
}

完整流程整合

class Vue {
  constructor(options) {
    this.$options = options
    this._data = options.data
    new Observer(this._data)
    Object.keys(this._data).forEach(key => {
      this.proxyData(key)
    })
    new Compiler(options.el, this)
  }

  proxyData(key) {
    Object.defineProperty(this, key, {
      get() {
        return this._data[key]
      },
      set(newVal) {
        this._data[key] = newVal
      }
    })
  }
}

以上代码实现了：

js实现v