TypeScript

TypeScript is a programming language that is a superset of JavaScript. It was developed by Microsoft and first released in 2012. TypeScript is designed to add optional static type checking to JavaScript, making it easier to develop large-scale applications.

TypeScript compiles to plain JavaScript and can run on any browser or JavaScript engine. The TypeScript compiler is available as a command-line tool or can be integrated into popular IDEs such as Visual Studio Code.

TypeScript adds several features to JavaScript, including:

Optional static typing: Variables, function parameters, and return types can be explicitly typed, and the compiler can check that types are used consistently throughout the code. This can help catch certain types of errors at compile-time instead of at run-time.
Class-based object-oriented programming: TypeScript supports class-based object-oriented programming with interfaces, inheritance, and encapsulation.
Type annotations and type inference: TypeScript can automatically infer types for variables and expressions, or types can be explicitly annotated for better readability and error checking.
Advanced features: TypeScript supports many advanced features, such as async/await, decorators, and generics.
TypeScript also includes the features of the latest ECMAScript standards and provides backward compatibility with earlier versions of JavaScript.

Why Using TypeScript over JavaScript?

• Strong typing: TypeScript provides optional static typing, which can help catch certain types of errors at compile-time instead of at run-time. This can improve the reliability and maintainability of your code, especially in large-scale applications.
• Better IDE support: TypeScript is designed to be used with modern development tools, and many popular IDEs, such as Visual Studio Code, provide excellent support for TypeScript. This can improve your productivity by providing better code completion, error checking, and debugging features.
• Improved code organization: TypeScript supports class-based object-oriented programming with interfaces, inheritance, and encapsulation. This can help you organize your code in a more modular and reusable way, making it easier to maintain and update over time.
• Backward compatibility with JavaScript: TypeScript is a superset of JavaScript and can be used with existing JavaScript code. This means that you can gradually adopt TypeScript in your projects and still leverage existing JavaScript libraries and frameworks.
• Growing community and ecosystem: TypeScript has a growing community of developers and is supported by major companies such as Microsoft, Google, and Airbnb. This means that there are many resources, tools, and libraries available for TypeScript development.

Syntax

See @thilliezTypeScriptSyntaxCheatsheets2023 (private) or https://www.typescriptlang.org/cheatsheets (public)

TsConfig

{
	"compilerOptions": {
		"lib" : [ "DOM", "ES6" ],
		"outDir": "dist",	
		"strict": true,		
		"target" : "ES3",
	}
}

tsconfig.json is a configuration file used by the TypeScript compiler to specify compiler options and other settings for a TypeScript project. It is a JSON file that must be located in the root of your project directory.

Here are some of the possible settings that can be specified in tsconfig.json:

• compilerOptions: This is an object that specifies the compiler options for TypeScript. Some of the most common options include:
• target: Specifies the ECMAScript version to target (e.g., "es5", "es6", "es2018", etc.).
• module: Specifies the module format to use (e.g., "commonjs", "es2015", "umd", etc.).
• outDir: Specifies the output directory for compiled files.
• strict: Enables strict type checking and other strict checks.
• noImplicitAny: Raises an error when an implicit any type is used.
• sourceMap: Generates a source map file to enable debugging of TypeScript code.
• esModuleInterop: Enables interoperability between CommonJS and ES modules.
• declaration: Generates .d.ts declaration files for your TypeScript code.
• include: Specifies the files to be included in the compilation process. This can be a list of file names or glob patterns.
• exclude: Specifies the files to be excluded from the compilation process. This can also be a list of file names or glob patterns.
• files: Specifies a list of individual files to be compiled.
• references: Specifies the projects that this project depends on.
• extends: Specifies a base configuration file to extend.

Map Files

map.js files are source map files generated by the TypeScript compiler when the sourceMap compiler option is set to true. These files allow developers to map the compiled JavaScript code back to the original TypeScript source code.

When you write TypeScript code, it gets transpiled to JavaScript code that can be executed by a browser or Node.js environment. However, this compiled code can be difficult to read and debug, especially if you are working with a large codebase. This is where source maps come in.

Source maps provide a mapping between the compiled JavaScript code and the original TypeScript code. This mapping allows developers to view and debug the TypeScript code directly in the browser or in their favorite debugging tools, even though the code that's actually running is the compiled JavaScript code.

The map.js file contains this mapping information. When a developer debugs the JavaScript code, the browser or debugging tool uses the source map file to display the corresponding TypeScript code.

META

Status:: #wiki/notes/mature
Plantations:: Programming Languages
References:: ILOG