One language can carry an application developer from web pages to mobile and desktop apps, and even cloud-based serverless projects. JavaScript’s reach makes its core mechanics worth understanding—not just its familiar-looking syntax. section 1.0
JavaScript’s C-like syntax can make it seem familiar to C# or Java programmers, but its function-oriented design works differently. Treating that resemblance as proof of familiarity can hide important distinctions. section 1.1
Key mechanics include:
- Functions are first-class objects: they can be created as literals, stored in variables, passed as arguments, and returned from other functions. section 1.1
- A closure occurs when a function retains access to external variables used in its body. section 1.1
- JavaScript uses prototype-based object orientation rather than the class-based approach associated with languages such as C# and Java. section 1.1
The browser is a central setting for JavaScript: client-side applications use the DOM to represent page interfaces and respond to events. Strong development practice also involves debugging, testing, and performance analysis. section 1.5
