Snippet

Metaprogramming with Proxies

The Proxy object allows you to create a wrapper for another object, which can intercept and redefine fundamental operations for that object, such as property lookup, assignment, and enumeration.

snippet.js

javascript

const user = {
  firstName: 'Jonas',
  lastName: 'Weber'
};
 
const handler = {
  get: (target, prop) => {
    if (prop === 'fullName') {
      return `${target.firstName} ${target.lastName}`;
    }
    return prop in target ? target[prop] : 'Property not found';
  }
};
 
const proxyUser = new Proxy(user, handler);
console.log(proxyUser.fullName); // Jonas Weber
console.log(proxyUser.age); // Property not found

Breakdown

const handler = { get: (target, prop) => { ... } };

Defines a 'trap' for getting property values.

const proxyUser = new Proxy(user, handler);

Creates the proxy by wrapping the original user object with the handler logic.

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Metaprogramming with Proxies

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