Backbone.js is one of the first popular JavaScript frameworks the web had seen. A few years ago, it was on extremely high demand and an employer would do anything to hire a good BackboneJS developer.
However, things have changed now with the emergence of Angular, Aurelia, React, Polymer, etc. Will you use Backbone.js today? If yes, what makes you do so?
What happens today, is that every Backbone developer wants to be good at React, Angular and other technologies as well, - at least this is what we have at our company. And thus they might use any needed technology for various cases, ‘cause sometimes you can use only one of them, and in this case there is no difficulty in the change of technologies, while they have experience with all of them.
Just see how many counties use Backbone.js:

Backbone JS was originally built to work with Rails.
I reckon using Backbone was a great way to understand how these front end frameworks work. Coupled with underscore.js, it helps to understand how certain functions and concepts work.
I use backbone on existing projects and will do on future projects. The reason is more a philosophical one, I agree with their principles and where my philosophy forks it is dead easy to fork the code.
I use backbonejs - for a lot of reasons. Using it on multiple projects. I too prefer simplicity and flexibility in a toolset. When it comes to abstraction of concerns and an event driven view state, nothing beats Backbone, in my opinion. And it gets us thinking about code abstraction, how we model code, and patterns - while we're building apps. And its fantastically extensible, and supports Prototypal Inheritance patterns.
I've used Backbone on three apps in the past year and it worked just great!
I still use it because the docs are great and it's not in a constant state of flux.
(see what I did there)
I still use Backbone.js. Why? It's more flexible than frameworks like Angular, React, ... because it does not provide a structure. Backbone is more a toolset than a framework. I have to think about my apps structure. I am the architect ;-).
In my eyes this flexibility of an toolset is an advantage, for many others it's a drawback. I like the idea to be able to set up my app from scratch.
As a JS developer i try to be independent from any framework. Frameworks come, frameworks go. If possible, i try to use pure vanilla.
Jennie B. Rogers
Well, its not dead. I'm still using Backbone.js. Backbone.js is a JavaScript front-end system that gives the structure and association to your application code, the occasion based correspondence for your application, and the fundamental interconnectedness for your information, application rationale, and UI.
Backbone the JavaScript MV structure is exploding the web advancement industry for its additional class highlights and functionalities. It engages you to create MVC (demonstrate see controller) sort applications and single-page applications. The main parts of Backbone.js advancement are Model, Collection, Router, View and Event class objects.
When working with Backbone you will find that the recovered information from the server put away by a model is in RESTful JSON way and is identified with the view. The view supplied by HTML is finished with help of JavaScript templating or by rendering system. The switch in the device demonstrations like a controller and is subject for dealing with a URL all things considered that it shows what code to keep running for which URL. well, you can follow this URL: goo.gl/im4A3X to know more about Backbone.js.