Generally it is not need to make a custom constructor method for a backbone Model. However if for some reason it is needed doing so is as simple as just adding one to the object that is passed to Backbone Model.extend, when making the Model.
In order to get started making a backbone model the first thing to do is use Backbone.Model.extend, and give it an object that will contain all of the methods, and objects that will be used to define the Model.
This will be a quick post on how to set, and work with default values in backbone. It sometimes just involves placing a defaults object of key and value pares, but things can become a little more complicated if you have a set method in the model.
In this post I will be writing a general overview of Models in backbone. This post will not cover everything there is to know about them, but it will be a good starting point, and I will link to any, and all other posts of mine that have to do with backbone Models.
After viewing a few terms on Google trends it appears that backbone.js is still popular these days. So as such I will commit to writing a few posts on it, and as always with this sort of thing, it will require a getting started type post.