harmony-reflect

What is harmony-reflect?

The harmony-reflect package is a library for ECMAScript 2015 (also known as ES6) that provides a full implementation of the ES6 Reflect API and Proxy handlers. It allows developers to intercept and define custom behavior for fundamental language operations (e.g., property lookup, assignment, enumeration, function invocation, etc.) using the Proxy API. It also provides utility functions that mirror the standard Reflect API, which provides methods for interceptable JavaScript operations.

What are harmony-reflect's main functionalities?

Proxying an object

This code demonstrates how to create a proxy for an object that returns the property value if it exists, or 42 if it does not.

{"handler": {"get": function(target, name) { return name in target ? target[name] : 42; }}, "proxy": new Proxy({}, handler)}

Reflecting property access

This code uses the Reflect API to access the property 'foo' on the target object.

{"target": {"foo": 1}, "status": Reflect.get(target, 'foo')}

Defining a property on an object

This code snippet uses Reflect.defineProperty to define a new property 'foo' on the target object with the value 123.

{"target": {}, "status": Reflect.defineProperty(target, 'foo', {value: 123})}

Observing function invocations

This code shows how to create a proxy for a function that intercepts the call and returns the result multiplied by 2.

{"handler": {"apply": function(target, thisArg, argumentsList) { return target.apply(thisArg, argumentsList) * 2; }}, "proxy": new Proxy(function(x) { return x; }, handler)}

Other packages similar to harmony-reflect

proxy-polyfill

The proxy-polyfill package provides a very limited polyfill for the Proxy object, which allows you to use a subset of the Proxy API features in environments that do not support it natively. It does not support the full range of metaprogramming capabilities that harmony-reflect offers.

reflect-metadata

The reflect-metadata package is a polyfill for the experimental metadata reflection API. It allows developers to add and read metadata on classes and properties. While it deals with reflection, it is more focused on metadata than the general proxy and reflection capabilities provided by harmony-reflect.

README

The README file is missing