[Javascript] Customize Behavior when Accessing Properties with Proxy Handlers

weixin_30429201

于 2019-05-31 22:17:00 发布

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CC 4.0 BY-SA版权

文章标签： javascript ViewUI

原文链接：http://www.cnblogs.com/Answer1215/p/10957810.html

博客介绍了在JavaScript中可拦截从对象获取属性值时的操作，在访问值之前执行特定行为。比如可检查属性名并返回特定值，或检查属性是否未定义并返回默认值，操作选择多样。

A Proxy allows you to trap what happens when you try to get a property value off of an object and do some behavior before the value is accessed. For example, you could check the name of the property and always return a certain value or even check if the property is undefined and return some default. The options are unlimited.

"use strict"

let person = {
  name: "John"
}

let handler = {
  get(target, key) {
    if (key === "name") {
      return "Mindy"
    }

    if (Reflect.has(target, key)) {
      return Reflect.get(target, key)
    }

    return "You tried to access something undefined"
  }
}

person = new Proxy(person, handler)

console.log(person.name) // "Mindy"
console.log(person.age) // "You tried to access something undefined"

转载于:https://www.cnblogs.com/Answer1215/p/10957810.html