InstanceProxy

Just an experiment created while playing with the Proxy API.

InstanceProxy

The InstanceProxy wraps all class instances in a Proxy using the construct trap.

const Foo = new InstanceProxy(
    class Foo {
        data = new Map();
    },
    {
        has(object, key) {
            return object.data.has(key);
        }
    }
);

const foo = new Foo(); // foo is wrapped in a Proxy

foo.data.set("bar", 42);

console.log("bar" in foo);

Proxied & ProxyHandler

Proxied & ProxyHandler are decorators which allow you to write instance proxies in a more comfortable way.

The @Proxied decorator looks for properties decorated with @ProxyHandler and creates a proxy handler.

The @ProxyHandler(trap) decorator marks the property as a proxy handler for the specified trap.

// This is the same as the example above
@Proxied
class Foo {
    data = new Map();

    @ProxyHandler("has")
    has(key) {
        return this.data.has(key);
    }
}

const foo = new Foo(); // foo is wrapped in a Proxy

foo.data.set("bar", 42);

console.log(foo.has("bar")); // These two lines are equivalent
console.log("bar" in foo);

Note: you should install & import the reflect-metadata package to use these decorators.