@twn39/juice

Juice is a small Dependency Injection Container for typescript and javascript.

Installation

Before using Juice in your project, add it to your package.json file:

$ pnpm i @twn39/juice

Usage

Creating a container is a matter of creating a Container instance:

import {Container} from '@twn39/juice'

const container = new Container();

As many other dependency injection containers, Juice manages two different kind of data: services and parameters.

Defining Services

A service is an object that does something as part of a larger system. Examples of services: a database connection, a templating engine, or a mailer. Almost any global object can be a service.

Services are defined by anonymous functions that return an instance of an object:

  container.set('LOGGER', (msg: string) => console.log(msg))

Notice that the anonymous function has access to the current container instance, allowing references to other services or parameters.

As objects are only created when you get them, the order of the definitions does not matter.

Using the defined services is also very easy:

const logger = container.get('LOGGER');

Defining Factory Services

By default, each time you get a service, Pimple returns the same instance of it. If you want a different instance to be returned for all calls, wrap your anonymous function with the factory() method

import {Container} from "@twn39/juice";

container.factory("SESSION", (c: Container) => new Session());

Now, each call to container.get('SESSION') returns a new instance of the session.

Protecting Parameters

Because Juice sees anonymous functions as service definitions, you need to wrap anonymous functions with the protect() method to store them as parameters:

container.protect('RANDOM', () => rand())

Modifying Services after Definition

In some cases you may want to modify a service definition after it has been defined. You can use the extend() method to define additional code to be run on your service just after it is created:

import {Container} from "@twn39/juice";

container.set('STORAGE', () => localStorage);
container.extend('STORAGE', (storage: LocalStorage, c: Container) => {
    return sessionStorage;
})

The first argument is the name of the service to extend, the second a function that gets access to the object instance and the container.

Extending a Container

If you use the same libraries over and over, you might want to reuse some services from one project to the next one; package your services into a provider by implementing IServiceProvider:

class FooProvider implements IServiceProvider {
  register(c: Container) {
      // register some services
  }
}

Then, register the provider on a Container:

container.register(new FooProvider());

Fetching the Service Creation Function

When you access an object, Pimple automatically calls the anonymous function that you defined, which creates the service object for you. If you want to get raw access to this function, you can use the raw() method:

container.set('SESSION', () => new Session());
const fn = container.raw('SESSION');