R.js

Ultralight solution for dependency injection, simple and framework independent.

Live demo

npm install rodi

Features:

• Provides a way to organize the code in modules
• Makes lazy loading and scalability easy, thanks to its trustful behavior (see details below)
• Allows to define modules that work seamlessly within NodeJs and inside the browsers
• Supports asynchronous module definition
• Keeps synchronous what can stay synchronous

Recommended: see the live demo, click on the yellow button and observe in browser console, to see an example of lazily loaded application area.

Usage:

R(key, dependencies, function);

to define an object with its dependencies

R(key);

to require an object

R([key1, key2, key3, ...])

to require an array of objects

Why is it easy to use?

1. R.js doesn't throw exception if a module is defined and its dependencies are not available: instead it waits until the dependencies will eventually become available
2. R.js only cares about the business logic and executing functions (no loading of JavaScript)
3. You can define as many modules as you desire in a single file: thanks to point 2., there is no connection between scripts location (src) and what they contain.

Examples:

• Hello World.

//defines HelloWorld; its dependencies are: "Hello" and "World"; gets resolved when both "Hello" and "World" becomes defined.
R("HelloWorld", ["Hello", "World"], function (Hello, World) {
  return Hello + " " + World;
});

//defines Hello
R("Hello", [], function () {
  return "Hello";
});

//defines World
R("World", [], function () {
  return "World";
});

• Asynchronous definition.

//defines "SomeModule", its dependency is "LateModule"; gets resolved when "LateModule" becomes defined
R("SomeModule", ["LateModule"], function (LateModule) {
  //this function is called when the "LateModule" becomes available
  //for example, this may happen when loading dynamically JavaScript with an AJAX call
  console.log("LateModule was resolved!");
  return "";
});

window.setTimeout(function () {
  //defines "LateModule" after 5 seconds
  R("LateModule", [], function () {  
    return "foo";
  });
}, 5e3);

• Functions to be called after some dependencies are ready

+function () {
  var k;
  
  //"Q" doesn't return anything, but depends upon "Something", therefore its function is called after "Something" function.
  R("Q", ["Something"], function () {
    //gets fired after "Something" function
    console.log("@", k);
  });

  //defines "Something": its function does not return anything; but interacts with external variable "k"
  R("Something", [], function () {
    k = 30;
  });
}();

How to debug

Since R.js is trustful and doesn't throw exception if a dependency is not resolved; it may happen that your code never gets executed because a key was misspelt. To understand which modules are not resolved and are waiting, you may call the method "queue", which returns the queue of modules waiting for definitions.

//call the queue function to see which modules are waiting for definitions of other modules
R.queue();

Another option is to set a "debug" property inside the R object to a truthy value. This way, R.js logs into console those dependencies that cannot be resolved immediately.

//NB: after r.js has been loaded (e.g. after the script element loading r.js)
//activate R.debug, so it logs the dependencies that cannot be resolved immediately
R.debug = true;