Chusha

Tiny Dependency Injection Container for JavaScript applications.

How to use

Installing

npm install --save chusha

Including Chusha

NodeJS

var Chusha = require('chusha') in your code to use it.

Browser

The production ready files are in the dist/ directory. There are two files, one minified and one not.

Chusha supports UMD-style modules, so it works with AMD and CommonJS. If you have no moduling system (You should!!), you can still access the Chusha object on the global window object.

Usage

To define dependencies for an object, implement a static inject() method on the object, which return an array of constructors

var HttpClient = require('./lib/HttpClient');

function MyObject(http) {
    this.http = http;
}
MyObject.inject = function() { return [HttpClient]; }

module.exports = MyObject;

Then, to grab a new object:

var MyObject = require('./MyObject');
var Chusha = require('chusha');

var obj = Chusha.get(MyObject);
// obj now contains an instantiated MyObject instance with the HttpClient injected.

To pass additional parameters into a constructor:

var HttpClient = require('./lib/HttpClient');

function MultiObject(http, server) {
    this.http = http;
    this.server = server;
}
MultiObject.inject = function() { return [HttpClient]; }

var obj = Chusha.get(MultiObject, "server-url");
// obj now contains an instantiated MultiObject instance with the HttpClient and server URL injected.

Dependency sharing

Sometimes, you'd want to share the same instance throughout all objects that need it (Database connection handlers, HTTP clients, etc).

You can use the Chusha.share() and Chusha.unshare() methods to add objects to a pool of shared objects.

var MyObject = require('./MyObject');
var Chusha = require('chusha');

Chusha.share({random: 'object'}, 'HttpClient'); // Share an object under the name 'http'.

var obj = Chusha.get(MyObject);
// obj now contains an instantiated MyObject instance with the HttpClient injected.

Chusha.share(obj[, hash])

Store object in the pool under the hash specified in the second argument.

If a second argument is not specified, Chusha will use the object's constructor name.

Chusha.share(new MyObject());
// same as Chusha.share(new MyObject(), 'MyObject');

Limitations

• You cannot share plain objects, functions or primitives.
• You cannot share two objects of the same constructor at the same time. Please explicitly call Chusha.unshare() before trying to share another instance of an object.

Chusha.unshare(hash)

Remove the object under the hash specified in the first argument from the pool.

Chusha.share(new MyObject());
Chusha.unshare('MyObject'); // Cancel the above statement.