AngularJS - simple example of how services, factories, and values work

gistfile1.js

// how services, factories, and values work

var foo = {
  providers:{},
  instances:{},
  provider:function(name,fn){
    var pName = name + 'Provider';
    foo.providers[pName] = foo.providers[pName] || new fn();
    foo.instances[name] = foo.instances[name] || foo.providers[pName].$get();
    return foo.providers[pName];
  },
  service:function(name,fn){
    if(foo.instances[name]){
      return foo.instances[name];
    }
    foo.provider(name,fn); // add the provider to providers
    return foo.instances[name] = new fn(); 
  },
  factory:function(name,fn){
    if(foo.instances[name]){
      return foo.instances[name];
    }
    foo.provider(name,fn); // add the provider to providers
    return foo.instances[name] = fn(); 
  },
}