legacy-decorators

A lightweight decorator which allows you to use decorators defined with the legacy syntax.

⚠️ Important

This doesn't actually work yet, and won't until this proposal is implemented. I'm not even sure if it will work once it is.

This package aims to support the old decorator syntax in modern javascript.

Usage

Simply import the @_ decorator from legacy-decorators, and give it a legacy decorator expression as an argument

import { @_ } from "legacy-decorators";
import { oldClassDecorator } from "./old-decorators.mjs";
 
@_(oldDecorator("arg1", "arg2"))
class C { }
 

import { @_ } from "legacy-decorators";
import { oldMethodDecorator } from "./old-decorators.mjs";
 
class C {
  @_(oldDecorator("arg1", "arg2"))
  method() {}
}
 

Explanation

In the legacy decorator syntax, a decorator was defined as any expression which evaluated to a function that took the arguments target (the target class or prototype), name (the name of the proporty or method, or undefined if a class is being decorated), and descriptor (the property descriptor for the property or method being decorated), and optionally returns an updated version of descriptor. The way decorators are defined has been overhauled completely, but this package allows you to continue using your older decorators by placing them as an argument for the @_ decorator (defined using the new syntax).

function legacyDecorator(arg) {
  return function decorator(target) {
    target.foo = arg
  };
}
 
// old syntax
 
@legacyDecorator("Hello, World!")
class C { }
 
// new syntax (with `legacy-decorators`)
 
import @_ from "legacy-decorators";
 
@_(legacyDecorator("Hello, World!"))
class C { }