There was a time when “backend” and “front‐end” developers were doing pretty different work. Backend developers were writing code to render web pages, using some server‐side language; front‐end developers were programming some interactivity using JavaScript and making the web pages look beautiful with CSS.

A few years ago, with the arrival of SPAs (Single Page Applications), JavaScript was not only used to add “some” interactivity, but was used to build the application itself. The skill‐set of the so‐called backend developers had to expand to include all the tools that were typical of front‐developers, such as specific JavaScript frameworks and some basic understanding of CSS.

The goal of this book is to explain the tools in “front‐end” developers’ toolbox and how to use them effectively in combination with ASP.NET Core MVC.


In everyday life, a polyglot is a person who knows and is able to use several languages. They are not necessarily bilingual (or multi‐lingual), but they can use their second or third or fourth language with a good level of proficiency.

With that definition in mind, what is a polyglot developer? It’s a developer who knows more than one (programming) language or framework and uses them within the scope of the same application.

From the beginning of IT industry, applications were mainly written in one language. I personally started with C, then moved to Visual Basic, landed on Cold Fusion, used JavaScript ...

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