ProxyTools

Thin wrappers that use JavaScript's Proxy class.

Documentation

Jump to tool:

• addAirlock
• addBouncer
• addDetour
• addLogger
• addQueue

addAirlock<T>(target: T, unlockers: (typeof T)[], ejectors: (typeof T)[])

• Stores all calls to target that don't match either unlockers or ejectors.
• If a method is called that matches unlockers, calls all stored methods and the unlocker method (in order).
• If a method is called that matches ejectors, forgets all stored methods and then stores the ejector method.

const counter = addAirlock(new Counter(0), ["increment"], ["decrement"]);
counter.increment();
assert.equals(counter.count, 1);
counter.double();
assert.equals(counter.count, 1);
counter.decrement();
assert.equals(counter.count, 1);
counter.increment();
assert.equals(counter.count, 1);

addBouncer<T>(target: T, isAvailable: () => boolean)

• Blocks all method calls to target while is isAvailable returns false.

const isAvailable = true;
const counter = addBouncer(new Counter(0), () => isAvailable);
counter.increment();
assert.equals(counter.count, 1);
isAvailable = false;
counter.double();
assert.equals(counter.count, 1);
isAvailable = true;
counter.decrement();
assert.equals(counter.count, 0);

addDetour<T>(target: T, detour: (prop: keyof T, args?: unknown[]) => void)

• Provides detour with target's traffic.
• If a property of target is being accessed, will pass the callback callback(${propertyName}, undefined).
• If a method of target is being called, will pass the callback callback(${methodName}, ${methodArgs}).

const counter = addDetour(new Counter(0), console.log);
counter.increment();
// > increment [];
counter.double();
// > increment []
counter.count
// > count undefined

addLogger<T>(target: T, logger: (str: string) => void, location?: string)

• Logs target's traffic.
• If property of target is being access, will pass logger ${location}.${propertyName}.
• If method of target is being called, will pass logger ${location}.${methodName}(${methodArgs}).

const counter = addLogger(new Counter(0), console.log, "counter");
counter.increment();
// > counter.increment()
counter.double();
// > counter.double()
counter.count
// > counter.count``

addQueue<T>(target: T, errHandler?: (err: Error) => void)

• Ensures that async methods are executed in order.
• Passes unhandled Promise errors to errHandler.

const waiter = addQueue({
  async waitOneSecond() { 
    // ...
    console.log("Waited one second");
  }
  async waitTenSeconds() {
    // ...
    console.log("Waited ten seconds");
  }
});
waiter.waitTenSeconds();
waiter.waitOneSecond();
// 10 seconds later > "Waited ten seconds"
// Then 1 second later > "Waited one second"