How can I Install TypeScript? & Can I start with TypeScript?

Install TypeScript

Setting up the project environment, installing the requisite tools, and integrating with external tools and development workflows are all typically included in the TypeScript setup process.

Prerequisites and Compiler Installation

TypeScript is a typed superset of JavaScript that outputs plain JavaScript as its output. The final JavaScript that you run on the server or in the browser is this created code.

The TypeScript compiler and an appropriate editor are usually needed to get started. It is an Open Source Software (OSS) program that can be accessed using the Node Package Manager (NPM).

Node.js and NPM: TypeScript Compiler (TSC) is a command-line program that is frequently installed with NPM in conjunction with Node.js. It takes Node.js to run JavaScript using the Google V8 JavaScript engine, which eliminates the need for a browser environment.

Installation Steps:

1. Install Node.js by downloading the appropriate installer.
2. Install the TypeScript compiler globally using the command line: npm install -g typescript.
3. Once installed, the TypeScript compiler command, tsc, is available. You can verify the installation and version using tsc -v.
4. Developers may choose to use the nightly version (typescript@next) as it incorporates newer features and benefits from continuous bug catching by the compiler test suite.

Project Configuration

The tsconfig.json file serves as the primary component that controls a TypeScript project. The directory’s very existence signifies that it is the root of a project that uses TypeScript.

The compilation context is defined by this configuration file, which also specifies the compiler parameters to be used and lists the files that TypeScript should parse and analyse.

Creation and Basic Structure: The tsc --init command speeds up the file’s generation. If the minimal tsconfig.json file is an empty JSON object {}, TypeScript will use sane default compiler choices and include all .ts files in the current directory (and subdirectories).

This property, compilerOptions, contains configuration settings:

• target: Specifies the ECMAScript target version for the output JavaScript (e.g., 'es5' or 'esnext').
• module: Dictates the generated module code format (e.g., 'commonjs', 'amd', 'es2015').
• outDir: Redirects the output JavaScript files (the compilation results) to a specific directory.
• lib: Specifies the ambient declaration files to be included, informing the TypeScript compiler about available global APIs such as the DOM or ES versions (e.g., "dom", "es6").
• strict: Enabling this option (e.g., "strict": true) enforces stringent type checking, significantly enhancing type safety.

Development Environment and Execution

Code Editors and Tooling

TypeScript is compatible with many different programming environments, including as Brackets, Atom, Sublime Text, WebStorm, and Visual Studio. VS Code, a well-known integrated development environment, is praised for its first-rate built-in TypeScript service and support. By enabling functions like code navigation, autocompletion, and refactoring tools, these language services greatly increase developer productivity. Via a .vscode/settings.json file, VS Code can also be instructed to utilise a locally installed version of TypeScript.

Compilation and Runtime

Transformation is the process of converting TypeScript (.ts) into JavaScript (.js) that can be run.

1. Manual Compilation: Use tsc Test.ts to launch the compiler after saving a .ts file (such as Test.ts). It produces Test.js. It is noteworthy that, as long as the syntax is valid JavaScript, the TypeScript compiler tries to generate JavaScript even in the wake of type problems.
2. Execution: Next, Node.js can be used to run the created JavaScript file, such as node Test.js.
3. Direct Execution: As an alternative, developers can use tools such as ts-node, which is a TypeScript equivalent of Node.js, to run .ts files directly, with the compilation process performed automatically.

Integrating with Tooling and Frameworks

Integration of TypeScript with contemporary build systems, linters, and testing tools is frequently necessary to achieve a production-ready setup.

Build Tools: Frontend apps need specialised compilers and packaging tools a lot.

• Webpack: Integration often involves installing ts-loader (npm install ts-loader --save-dev) and configuring webpack.config.js.
• Browserify: Installing the tsify plugin is necessary.
• Other tools supported are Grunt and Gulp, which need certain plugins like grunt-ts or gulp-typescript.

Linters and Testing:

• Linting: While TSLint was historically used (tslint.json configuration), modern setups often use ESLint with specific TypeScript parser and plugin packages, such as @typescript-eslint/parser and @typescript-eslint/eslint-plugin, to enforce quality and style.
• Unit Testing (Jest): To use Jest with TypeScript, developers install jest, @types/jest, and the TypeScript preprocessor ts-jest to handle on-the-fly transpilation.
• E2E Testing (Cypress): TypeScript definitions are pre-installed in Cypress for E2E testing. Advanced configurations can manage dependencies and prevent conflicts with global type definitions by using a distinct e2e folder and tsconfig.json file.

Framework Integration (React/Node.js):

• React: Requires files to use the .tsx extension, configuring "jsx": "react" in tsconfig.json, and installing type definitions for React and React DOM (@types/react, @types/react-dom).
• Node.js: The quick setup of Node.js includes installing typescript, initialising package.json, and adding types for Node APIs (@types/node) for developer safety and ergonomics.

Progressive Adoption and Third-Party Support

Since all legitimate JavaScript is also legitimate TypeScript, TypeScript is intended for gradual adoption. To facilitate the change, migration procedures usually entail renaming files from .js to .ts progressively and utilising compiler options.

JavaScript Interoperability: By turning on the allowJs compiler option, TypeScript can include plain JavaScript files in its compilation context. The checkJs tool can be used to provide optional type checking on these files.

Third-Party Libraries: TypeScript uses Declaration Files (.d.ts) to supply type information for existing code because a lot of well-known libraries are written in JavaScript. Installing the definitions for the most widely used JavaScript libraries using NPM under the @types scope (e.g., npm install @types/jquery) is done by the DefinitelyTyped community. With complete type safety and code intelligence, developers can use external JavaScript code with ease and safety thanks to this technology.

Start with TypeScript

Yes, you can certainly start with TypeScript, particularly if you already possess fundamental knowledge of JavaScript (variables, functions, classes, and scope). TypeScript is explicitly designed as a superset of JavaScript, meaning all valid JavaScript code is also valid TypeScript. This crucial feature means you can start by simply renaming your existing .js files to .ts files, allowing for incremental upgrading without needing a complete rewrite.

To begin using it, developers need the TypeScript compiler (TSC), which is available as an open-source software (OSS) package on NPM. You can install the compiler globally via the command line using the Node Package Manager: npm install -g typescript.

For initial experimentation without installing anything locally, the TypeScript Playground is an excellent online editor supporting full IDE features like auto-completion and static type error display.

The language’s basic principles are relatively easy to grasp; sources suggest you can learn the essentials within a day and be productive almost immediately. TypeScript provides valuable structure, allowing for early error detection and enhanced tooling support to help developers write more reliable applications.