counter.js

'use strict';

function counter($timeout){
  var i = 0;
  return (function(){
    i += 1;
    return i;
  });
}

module.exports = {
  counter: counter
};

counter2.js

'use strict';

function counter2($timeout){
  return (function(){
    this.count += 1;
    return this.count;
  })
}

module.exports = {
  counter2: counter2
}

counter3.js

'use strict';

function counter3($timeout){
  var i = 0;
  return (function(){
    // do something with $timeout or other services
    i += 1;
    return i;
  });
}

module.exports = {
  counter3: counter3
};

counter4.js

'use strict';

function counter($timeout){
  var i = 0;
  return (function(){
    i += 1;
    return i;
  });
}

module.exports = {
  counter: counter
};

main.js

'use strict';

require('./setup')(function(angular){
  var c = require('./counter');

  angular
    .module("app", [])
    .factory("counter", ["$timeout", c.counter])
    .service("useCounter1", function(counter){return {use: counter};})
    .service("useCounter2", function(counter){return {use: counter};})
  ;

  var inj = angular.injector(["ng", "app"]);
  var c1 = inj.get("useCounter1");
  var c2 = inj.get("useCounter2");

  console.log(c1.use());
  console.log(c2.use());
  console.log(c1.use());
});

main2.js

'use strict'

require('./setup')(function(angular){
  var c = require('./counter2');

  angular
    .module("app", [])
    .factory("counter", ["$timeout", c.counter2])
    .factory("useCounter1", function(counter){
      var state = {count: 0};
      return {
        use: counter.bind(state)
      };
    })
    .factory("useCounter2", function(counter){
      this.count = 0;
      return {
        use: counter.bind(this)
      };
    })
  ;

  var inj = angular.injector(["ng", "app"]);
  var c1 = inj.get("useCounter1");
  var c2 = inj.get("useCounter2");

  console.log(c1.use());
  console.log(c2.use());
  console.log(c1.use());
});

main3.js

'use strict';

require('./setup')(function(angular){
  var c = require('./counter3');

  angular
    .module("app", [])
    .factory("useCounter1", function($timeout){
      return {
        use: c.counter3($timeout)
      };
    })
    .factory("useCounter2", function($timeout){
      return {
        use: c.counter3($timeout)
      };
    })
  ;

  var inj = angular.injector(["ng", "app"]);
  var c1 = inj.get("useCounter1");
  var c2 = inj.get("useCounter2");

  console.log(c1.use());
  console.log(c2.use());
  console.log(c1.use());
});

main4.js

'use strict';

require('./setup')(function(angular){
  var c = require('./counter');

  function counterFactory($timeout){
    return function(){
      return c.counter($timeout);
    };
  }

  angular
    .module("app", [])
    .factory("counter", ["$timeout", counterFactory])
    .service("useCounter1", function(counter){return {use: counter()};})
    .service("useCounter2", function(counter){return {use: counter()};})
  ;

  var inj = angular.injector(["ng", "app"]);
  var c1 = inj.get("useCounter1");
  var c2 = inj.get("useCounter2");

  console.log(c1.use());
  console.log(c2.use());
  console.log(c1.use());
});

package.json

{
  "name": "singleton-or-factory",
  "version": "1.0.0",
  "description": "",
  "main": "main.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "angular": "^1.4.8",
    "benv": "^3.0.0"
  }
}

setup.js

'use strict';
var benv = require('benv');

function setup(cb){
  benv.setup(function(){
    global.Node = window.Node;
    benv.expose({
      angular: benv.require(require.resolve("angular/angular"), "angular")
    });
    cb(window.angular);
  });
}

module.exports = setup;

npm install
node main.js
node main4.js