What advantages are gained by using constructors in JavaScript?

Question

I'm working to refactor a large and undocumented JavaScript Library. One of the proposed refactorings is to implement constructors in the code as opposed to dynamically constructing an object. Example Below:

Instead of:

var myLibObj = new Object();
myLibObj.SomeProperty =
{
   FooFunction: function(){/*Do Something Cool*/}
}

The proposed change:

function myLibObjConstructor(){
  this.SomeProperty = {FooFunction: function(){/*Do Something Cool*/}}
  return this;
}

var myLibObj = new myLibObjConstructor();

Is there any advantage to changing the code?

good question! but possible dupe of http://stackoverflow.com/questions/4508313/advantages-of-using-prototype-vs-defining-methods-straight-in-the-constructor and http://stackoverflow.com/questions/1595611/how-to-properly-create-a-custom-object-in-javascript — matchew, Jun 09 '11 at 14:33

score 2 · Accepted Answer · answered Jun 09 '11 at 14:28

2

One advantage would be that myLibObjConstructor can be reused somewhere else

answered Jun 09 '11 at 14:28

Lourens

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That's also a pretty huge advantage, and one of the most basic principles of good programming. – Svend Jun 09 '11 at 14:32

score 1 · Answer 2 · answered Jun 09 '11 at 14:45

If it's existing code that already works without the need for constructors, the benefits of moving toward constructors could be marginal or non-existent.

However, the general advantages of using constructors would be:

Object instances have a "type" i.e. you can check instanceof or constructor to make decisions given just an object instance.
The most important of all, you get encapsulation. You can encapsulate "private" properties, inheritance etc., leading to cleaner and more portable code.
Using a constructor is more concise and more conventional than instantiating a generic object first and tacking on properties.