Javascript return with colon

Question

I am learning JavaScript and have come across of the structure below:

var Test = (function () {

  function func1() {
      //do something.....
  }

  functi         


        

Answer 1

It's a literal object in the return statement. It's like creating an object and then returning it:

var obj = {
    func1: func1,
    func2: func2,
    func3: func3
};
return obj;

The literal object syntax creates an object and sets its properties, just like:

var obj = new Object();
obj.func1 = func1;
obj.func2 = func2;
obj.func3 = func3;
return obj;

The purpose of returning the object is to reveal the functions inside the function to the code outside, while creating a scope for private variables that the functions can use.

When not using private variables, the code does the same thing as:

var Test = {
  func1: function() {
      //do something.....
  },
  func2: function() {
      //do something.....
  },
  func3: function() {
      //do something.....
  }
};

Private variables are declared inside the function scope, and are only reachable by the functions inside it. Example:

var Test = (function () {

  var name;

  function setName(str) {
    name = str;
  }

  function getName() {
    return name;
  }

  return {
      setName: setName,
      getName: getName
  };

})();

Test.setName("John Doe");
var name = Test.getName();