longlh/di-linker

A lightweight Dependency Injection Framework for JS

DI-Linker 2.1.2

di-linker is a lightweight Dependency Injection for Javascript. It provides some main features:

• No more hard-coded dependencies
• No more confusing require statement
• Scan source codes, wire them together then bootstrap main module
• Work both in server and client

Server

Installation

npm install di-linker

Wire your codes

Prepare source codes:

// index.js
var di = require('di-linker');
var sources = [
  'app/**/*.js'
];

di.walk(sources, require).then(function(context) {
  return context.bootstrap(['/main']); // entry point
}).catch(console.error.bind(console))

// app/main.js
exports.name = '/main';
exports.requires = [
  '/lib' // wire `/lib` module
];
exports.factory = function(lib) {
  // use `lib` here
  console.log('`lib` module injected');
};

// app/lib.js
exports.name = '/lib';
exports.requires = [
  '@fs', // require `fs` package
  '@path' // require `path` package
];
exports.factory = function(fs, path) {
  return {
    fs: fs,
    path: path
  };
};

That is all, now you can run your application:

node ./index.js

Define modules

• exports.name {String} Define module name
• exports.requires {Array} Define the module's dependencies. Note that @ prefix means requiring Node packages
• exports.factory {Function} Define a function as factory for the module. Module's dependencies are injected as parameters of this function
• exports.activations {Array} List of other modules need be activated after the module initialized (can be omitted)
• exports.value {Object} Use a specified value insteads of factory. This option will override factory option

Client

Installation

bower install di-linker

Wire your codes

In HTML:

<script src="bower_components/di-linker/dist/di-linker.standalone.min.js"></script>

In Javascript:

var context = __('app_name');

context.factory('main', [
  'lib',
  function(lib) {
    // lib is injected and can be used here
  }
]);

context.factory('lib', [
  function() {
    return {
      veryUsefulFunction: function() {}
    };
  }
]);

context.bootstrap(['main']);

Built-in modules for client-side

Because di-linker use lodash and bluebird internally, so those modules are built-in. They can be injected via reversed words @lodash and @bluebird.

__('app_name').factory('lib', [
  '@lodash',
  '@bluebird',
  function(_, Promise) {
  }
]);

APIs

Context is core class of di-linker. It can be created by the following methods:

Server-side:

var di = require('di-linker');

// scan code folder and return a context instance via promise
di.walk(patterns).then(function(context) {

});

// another way
var newContext = di('context_name');
var sameContext = di('context_name');
var anotherConctext = di('another_context_name');

console.log(newContext === sameContext);      // true
console.log(newContext === anotherContext);   // false

// another way
var context = new di.Context();

Client-side:

// get a context instance via global function `__`
var newContext = __('context_name');
var sameContext = __('context_name');
var anotherConctext = __('another_context_name');

console.log(newContext === sameContext);      // true
console.log(newContext === anotherContext);   // false

// another way
var context = new __.Context();

Methods

context.register(def)

• def {Object}
  • name {String} Define module name
  • requires {Array} Define the module's dependencies. Note that @ prefix means requiring Node packages
  • activations {Array} List of other modules need be activated after the module initialized (can be omitted)
  • factory {Function} Define a function as factory for the module. Module's dependencies are injected as parameters of this function
  • value {Object} Use a specified value insteads of factory. This option will override factory option
• return: current context

Register a dependency

context.value(name, value)

• name {String} Dependency name
• value {Object} Dependency value, will be injected
• return: current context

Sugar method of context.register() for value-type dependency, with name and value only

context.factory(name, def)

• name {String} Dependency name
• def {Array} Last element is factory function, other are name of dependencies need to injected
• return: current context

Sugar method of context.register() for factory-type dependency, width name, requires and factory only

context.bootstrap(modules)

• modules {Array} Array of module name that need to execute
• return: a promise that resolve the current context when bootstrap is done

Execute some modules that registered already in the context

context.config(preferences)

• preferences {Object} Key-value map of the preferences
  • verboseLog {Boolean} Enable verbose log for resolving and resolved states
  • allowReRegister {Boolean} Allow to re-register existing module. Only use this option for mocking dependencies in testing
• return: current context

Tests

$ npm install
$ npm test

License

The MIT License