Question 58

Question

Can you explain how to use proxy.revocable property to revoke a proxy object?

Answer

The proxy.revoke() method is crucial for managing Proxy objects effectively, allowing you to break the association between your proxy and the original target object.

Here's how it works:

const handler = { get: value => console.log(`Getting: ${value}`) }; 
const myProxy = new Proxy({ name: 'Alice' }, handler);

// ... use the proxy as usual... 

console.log(myProxy.name); // Outputs "Getting: Alice"

// Revoke the proxy
const {revoke} = myProxy;  
revoke();

// Now, trying to access the proxy will throw an error
console.log(myProxy.name); // Throws TypeError: Cannot read property 'name' of undefined

Explanation:

1. Creating the Proxy: We define a handler and create a Proxy object targeting an object with the property name.

2. Using the Proxy: The code demonstrates accessing the name property through the proxy, triggering the get handler to log "Getting: Alice".

3. Revocation: We access the revoke() function from the proxy itself (it's an internal property). Calling revoke() effectively undoes the association between the proxy and its target object.

4. Consequences of Revocation:

   • Any subsequent attempts to access properties through the revoked proxy will throw a TypeError. The proxy is no longer valid.

   • The original target object remains unchanged.

Important Points:

• revoke() acts immediately; it doesn't wait for the next operation on the proxy.

• Use revocation when you need to release resources associated with the proxy, or when you want to prevent further manipulation of a target object after a certain point in your code.