vue中defineProperty和Proxy的区别详解

// vue 2.5.0
var arrayProto = Array.prototype;
var arrayMethods = Object.create(arrayProto); // Array {}
function def(obj, key, val, enumerable) {
  Object.defineProperty(obj, key, {
   value: val,
   enumerable: !!enumerable,
   writable: true,
   configurable: true
  });
}
var methodsToPatch = [
  'push',
  'pop',
  'shift',
  'unshift',
  'splice',
  'sort',
  'reverse'
  ];

  /**
  * Intercept mutating methods and emit events
  */
  methodsToPatch.forEach(function(method) {
  // cache original method
  var original = arrayProto[method]; 
    // 比如 method是push，则结果为
    // ƒ push() { [native code] }
  def(arrayMethods, method, function mutator() {
   var args = [],
   len = arguments.length;
   while (len--) args[len] = arguments[len];

   var result = original.apply(this, args);
   var ob = this.__ob__;
   var inserted;
   switch (method) {
   case 'push':
   case 'unshift':
    inserted = args;
    break
   case 'splice':
    inserted = args.slice(2);
    break
   }
   if (inserted) {
   ob.observeArray(inserted);
   }
   // notify change
   ob.dep.notify();
   return result
  });
  });
  
  /**
  * Observe a list of Array items.
  */
  Observer.prototype.observeArray = function observeArray(items) {
  for (var i = 0, l = items.length; i < l; i++) {
   observe(items[i]); // 后续的逻辑
  }
  };

  let proxy = new Proxy(fruit, {
    get: function (obj, prop) {
      return prop in obj ? obj[prop] : undefined

    },
    set: function (obj, prop, newVal) {
      obj[prop] = newVal
      console.log("newVal", newVal) // 输出{ name: "lemon", num: 999 }
      return true;
    }
  })
  proxy.push({ name: "lemon", num: 999 })
  console.log(fruit)

   let fruit = {
     "apple": 2,
     "pear": 22,
     "peach": 222
  }
  Object.keys(fruit).forEach(function (key) {
      Object.defineProperty(fruit[i], key, {
        enumerable: true,
        configurable: true,
        get: function () {
          return val;

        },
        set: function (newVal) {
          val = newVal; // 输出 newVal 888
          console.log("newVal", newVal)
        }
      })
    })
   fruit.apple = 888

   let fruit = {
     "apple": 2,
     "pear": 22,
     "peach": 222
  }
  let proxy = new Proxy(fruit, {
    get: function (obj, prop) {
      return prop in obj ? obj[prop] : undefined

    },
    set: function (obj, prop, newVal) {
      obj[prop] = newVal
      console.log("newVal", newVal) // 输出 newVal 888
      return true;
    }
  })
  proxy.apple = 888

<div id="app">
  <span v-for="(value,name) in fruit">{{name}}:{{value}}个 </span> 
  <button @click="add()">添加柠檬</button>
</div>
<script src="https://unpkg.com/vue"></script>
<script>
  new Vue({
    el: '#app',
    data() {
      return {
        fruit: {
          apple: 1, 
          banana: 4, 
          orange: 5 
        }
      }
    },

    methods: {
      add() {
          this.fruit.lemon = 5;  // 不会让视图发生变化
        // this.$set(this.fruit,"lemon",5)  // this.$set可以
      }
    }
  })
</script>

  Object.keys(fruit).forEach(function (key) {
    Object.defineProperty(fruit, key, {
      enumerable: true,
      configurable: true,
      get: function () {
        return val;

      },
      set: function (newVal) {
        val = newVal;
        console.log("newVal", newVal) // 根本没有进去这里
      }
    })
  })

// vue 3
<div id="app">
  <span v-for="(value,name) in fruit">{{name}}:{{value}}个 </span>
  <button @click="add()">添加柠檬</button>
</div>
<script src="https://unpkg.com/vue@next"></script>
<script>
  Vue.createApp({
    data() {
      return {
        fruit: {
          apple: 1,
          banana: 4,
          orange: 5
        }
      }
    },

    methods: {
      add() {
        this.fruit.lemon = 5; // 这样子是可以的
      }
    }
  }).mount('#app') // vue 3 不再是使用el属性，而是使用mount
</script>

  let proxy = new Proxy(fruit, {
    get: function (obj, prop) {
      return prop in obj ? obj[prop] : undefined

    },
    set: function (obj, prop, newVal) {
      obj[prop] = newVal
      console.log("newVal", newVal) // lemon, 888
      return true;
    }
  })
  proxy.lemon = 888

// server.js
// 假设这里都是回调
export const searchResultList = function (data, callback, errorCallback) {
 axios.post(url, data, callback, errorCallback)
}

// promisify.js
import * as server from './server.js'
const promisify = (name,obj) => (option) => {
 return new Promise((resolve, reject) => {
  return obj[name](
   option,
   resolve,
   reject,
  )
 })
}
const serverPromisify = new Proxy(server, {
 get (target,prop) {
  return promisify(prop, server)
 }
})
export default serverPromisify

// index.js
import serverPromisify from './serverPromisify'
serverPromisify.searchResultList(data).then(res=>{

})