Over the last two decades, JavaScript has grown from enabling developers to perform simple interactions with in-browser HTML to being the core of enterprise applications, both frontend and backend. This success has become more apparent with the advent and creations of NodeJS, Cordova, Ionic, and serverless frameworks, all of which have adopted and support TypeScript. This growth, coupled with the ever-increasing demand for complex and performant JavaScript, has fueled the need for stricter typing, structures, and code decoupling.
TypeScript, created by Microsoft, is the long-awaited solution to these needed language constructs. It is a superset of JavaScript, allowing for compilation to JavaScript and for JavaScript to run within TypeScript. TypeScript is both open source and has backing from major JavaScript libraries and frameworks, namely React, Angular, Express, Knockout, and Ionic. This backing is evidence alone that TypeScript has garnered support from the cutting edge in the industry.
With this evolution, it is necessary for learning to take place for newbies and gurus alike. This book has been designed to walk through various topics of the language, building into meaningful constructs to help you, as a TypeScript developer, build scalable, efficient, and maintainable applications from the first line of code. We start by walking you through language structure and terminology, continue through optimizing your code to load quickly and fine-tune performance, and wrap up with a discussion on building and deploying applications for large-scale and enterprise applications.
TypeScript is here to stay and will be looked back upon as the next iteration of JavaScript just as its predecessors, such as Prototype, jQuery, Dojo, and Mootools, were. This book will walk you through the language and will explain how to write efficient enterprise TypeScript to scale.
This book has been assembled in topics that allow you to focus on your topics of interest. Although we have tried to build self-contained chapters and sections, we highly recommend reading each chapter thoroughly, as the latter sections in the book build on material from the initial chapters.
Chapter 1, Efficient Implementation of Basic Data Structures and Algorithms, covers the efficient implementation of basic TypeScript data structures, data types, and flow control with the help of classic algorithms.
Chapter 2, Variable Declarations, Namespaces, and Modules, describes the distinction and correct usage of variable declarations. It also describes code organization strategies, namely leveraging namespaces and modules.
Chapter 3, Efficient Usage of Advanced Language Constructs, covers several different language constructs in TypeScript. It explains how to use them, the scenarios in which to use each construct, and their efficient usage.
Chapter 4, Asynchronous Programming and Responsive UI, is a deep dive into the world of asynchronous programming. We walk you through the massive performance hits your application can take if not built correctly, and we discuss strategies and tips for efficient coding.
Chapter 5, Writing Quality Code, covers the several configurations available with TSLint and how they can be used to improve code quality and performance.
Chapter 6, Efficient Resource Loading - Critical Rendering Path, introduces the critical rendering path and the steps involved in the process of loading a web application. We discuss strategies for quick and non-blocking resource loading to produce a highly responsive and performant application load.
Chapter 7, Profile Deployed JS with Developer Tools and Fiddler, introduces the concept of profiling and the tools available. We compare the performance results of quality code written with the help of TSLint and compare it to poorly written TypeScript code.
Chapter 8, Building and Deploying Strategies for Large Scale Projects, covers the build and deployment process of real-world, enterprise-scale TypeScript applications.
The book requires the following things:
- Node and NPM
- TypeScript
- Mocha Test Framework
- Chai Assertion Library
- Windows, Linux, or MacOS
- Modern browsers--Chrome, Edge, and IE
- Telerik Fiddler
- Frontend editor--preferably VS Code or Atom/Sublime Text
The scope of this book is broad, as are the applications and solutions that can be delivered through TypeScript. As such, this book is essential for those who have a passion for software at every stage of the life cycle, from ideation to architecture, design, build, and test. This book should appeal to people who have embraced TypeScript for years and people who have been in the JavaScript world and have debated making the jump to TypeScript.
Basic knowledge of TypeScript and some experience using JavaScript are prerequisites for this book.
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning. Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Since the text variable was not previously defined, the log output will now display a compilation error." A block of code is set as follows:
// const tests
function constTest(): () => number {
const x: number = 16;
x = 4; // Left-hand side of assignment expression cannot be
a constant
return function innerFunction(): number {
x++; // the operand of an increment or decrement operator
cannot be a constant
return x;
}
}
console.log('const test: ', constTest()());When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
[default]
exten => s,1,Dial(Zap/1|30)
exten => s,2,Voicemail(u100)
exten => s,102,Voicemail(b100)
exten => i,1,Voicemail(s0)Any command-line input or output is written as follows:
ts-mocha test.tsNew terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Let's take a look at the Network tab of the Developer Tools."
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