[Javascript] Customize Behavior when Accessing Properties with Proxy Handlers

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.

 

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"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"

  

posted @   Zhentiw  阅读(136)  评论(0编辑  收藏  举报
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