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What is Knockout.js?

As JavaScript has continued to emerge as one of the preeminent programming languages in modern web development, the demand for JavaScript frameworks and libraries has continued to increase. Since JavaScript offers versatility and a wide range of features for developing everything from basic mobile apps and programs to powering complex new technologies like machine learning and the Internet of Things, it’s no surprise that powerful JavaScript frameworks are needed to simplify and improve development to meet these needs.

There are plenty of useful JavaScript frameworks, including jQuery, Angular.js, Express, and others, and one of the most popular choices among developers these days is Knockout.js. But what is Knockout.js? A minimalist JavaScript framework for web application development, Knockout.js works with any type of server-side and client-side technologies, making it one of the more widely useful JavaScript frameworks available.

From developing dynamic user interfaces to powering some of the most popular websites on the Internet, Knockout.js’ footprint is growing by the day. But what are the unique features and use cases that help this framework stand out from the pack? What coding fundamentals would you need to learn to work with Knockout.js for your next project? This guide will cover the basic structure of the framework, as well as some of the best reasons to consider choosing Knockout.js for your development and programming needs.


What is the structure of Knockout.js? 

At its basic level, Knockout.js is a JavaScript library that offers the ability to bind HTML elements against any data model. It is most often used for creating rich and responsive displays for users, as well as intuitive editor user interfaces with a clean, underlying data model. As noted above, Knockout.js integrates well with any type of client-side or server-side technologies.

To better understand the different elements of what makes Knockout.js useful, it’s also important to know that the specific classes of different frameworks used in modern web development – notably, MVC and MVVM. Knockout.js is a JavaScript implementation of the MVVM pattern with templates, which offers several specific advantages over competing frameworks. Here are some of the most notable:

MVVM Framework Features 

Knockout.js offers the MVVM or “Model–View–View Model” application design architecture. The acronym represents the different elements that constitute the structure of the framework, specifically:

  • Model – A Model represents data or information, storing the information but not the additional behaviors or services that manipulate the information.  It is done with assistance from the View and View Model, as they both are interconnected through a two-way data binding mechanism.
  • View – A View is the actual representation or construction of the data for the end user. A view is an HTML template which includes Knockout bindings. The view incorporates data-bind attributes to display and edit data, while also containing HTML elements like buttons, images, grids, links and more.
  • View Model – A View Model serves as the intermediary between the Model and the View. In the case of Knockout.js, it is a unique JavaScript representation of the model data, as well as the associated functions used to manipulate the data.

MVVM frameworks are specifically optimized for creating dynamic user interfaces, simplifying app and web development by achieving separation of concerns. For example, frameworks like this separate GUI (graphical user interface) rendering logic from application logic.

Declarative Binding

Because business applications and REST services often require client-side ability to display data to users, code complexity is often an issue that can cause programming in JavaScript to rely on onerous and time-consuming code-writing with JQuery. In addition to being a complicated process, this also generally requires writing extensives lines of code.

However, Knockout.js allows embedding data binding expressions in your HTML, as well as associating DOM elements with model data using a simple syntax. Additionally, Knockout.js is a data-binding library and allows developers to create custom bindings inside data-bind and declarative binding to connect parts of a project’s user interface to the required data model. 

The ability to incorporate custom behaviors as new declarative bindings for easy reuse in just a few lines of code can save developers tons of time and effort and avoid the formerly frustrating process that this would have required.

Additionally, Knockout.js also incorporates a two-way data binding mechanism between the UI and data model, which means that any edits or changes added to the data model are automatically displayed in the UI, and vice versa. UI elements of an HTML page reflect changes done to the Data Model by updating DOM automatically. 

Native Templating 

Knockout.js offers DOM-based templating, and as a default utilizes HTML as its templating engine, while also supports other string-based templating. Templating like this allows applications to render views that are modular and reusable, removing the need to create views over and over again. By using Knockout.js, a developer can perform DOM or string-based templating for modularizing views, as well as rendering them in a programmed way. Furthermore, Knockout.js also offers users the ability to create templates to render HTML for a single element or for every element in an array, making code organization much easier and more efficient than other alternative JavaScript frameworks.

Dependency Tracking 

Because Knockout.js automatically tracks dependencies and dynamically updates the appropriate parts of the user interface, the framework offers a remarkably simple way to manage complex, data-driven interfaces without needing to rely on or write event handlers and listeners for dependency tracking.

Observables are at the core philosophy of Knockout.js. Observables are JavaScript objects which notify subscribers about changes, as well as automatically detected dependencies. Within the framework, computed observables are used to define data fields, while declarative bindings are cleanly implemented as computed observables. As a result of this, when a binding reads the value of an observable, it leads to the binding reevaluating if/when the observable changes.

No Dependencies 

Because Knockout.js has no dependencies and doesn’t require jQuery, Prototype.js, or any other JavaScript library, it offers significant flexibility and streamlining that some other JavaScript frameworks can’t claim themselves. It supports multiple browsers, such as Opera, Chrome, Safari, Internet Explorer, and Firefox, and works without significant extra time in integrating with other tools or extensions.

Open Source 

While open sourcing has been rapidly becoming a norm among modern programming tools and frameworks, Knockout.js also includes all of the benefits that open-sourcing entails. Namely, as the community of developers using Knockout.js continues to grow, the growing library of online tutorials, app examples, FAQs and answers, and documentation available on the Knockout.js website continues to grow as well. In addition, popular developer website hubs like Stack Overflow and Github also feature thriving communities and resource hubs for developers getting their feet wet with the Knockout.js framework.

So how can I learn to use Knockout.js? 

Like learning any new programming tool, it’s important to start by learning the basics first – in this case, making sure you know all of the fundamental techniques and structural elements of the base language, JavaScript. One of the best ways to do this is to use an online coding class app like SoloLearn, which offers a variety of useful learning tools for anyone trying to master one of the modern and popular programming languages, such as:

  • A diverse set of tutorials included within the JavaScript course, which cover the fundamental features and knowledge required to learn the language and what it can be used for.
  • Practice exercises to ensure you have mastered the concepts and can apply them in real world scenarios
  • An ever-growing code playground, where you can actually play around with live code and apply the lessons from different tutorials to see how a program is actually created.
  • A thriving learner community that offers a variety of opportunities for collaboration, getting questions answered, and even challenging fellow learners to coding competitions.
  • A unique learner profile, where you can track learning achievements and progress toward milestones to help keep yourself motivated while you learn!

Once you have mastered JavaScript and gained some experience with the functions of the language, the Knockout.js website offers a variety of interactive tutorials and, as mentioned earlier, an ever-growing hub of developers sharing best practices and teaching tools as they continue to experiment with the framework for their own projects.