Documentation

Typescript

Comprehensive documentation for typescript

TypeScript Documentation

This guide introduces TypeScript programming theory, focusing on concepts and best practices for developers using the Codeunia Learn platform.

Overview

TypeScript is a superset of JavaScript that adds static typing, enhancing code reliability and maintainability. It compiles to plain JavaScript, allowing seamless integration with existing JS ecosystems. TypeScript supports object-oriented and functional programming paradigms, making it suitable for large-scale applications.

TypeScript Fundamentals

Variables and Data Types

Variables are declared with let or const, and types can be explicitly annotated. TypeScript introduces static typing while maintaining JavaScript's dynamic nature. Common data types include:

  • String: Textual data.
  • Number: Numeric values (integers and floats).
  • Boolean: True or False values.
  • Array: Ordered collections.
  • Tuple: Fixed-length arrays with known types.
  • Enum: Named constants.
  • Any: Opt-out of type checking.
  • Void: Absence of any type.
  • Null and Undefined: Specific absence values.

Type annotations use syntax like let variable: Type.

Strings

Strings support template literals for interpolation and multi-line strings. Methods for manipulation include slicing, replacing, and case conversion.

Arrays

Arrays are typed collections, supporting generic types like Array<Type> or Type[]. They include methods for iteration, transformation, and mutation.

Objects and Interfaces

Objects represent structured data. Interfaces define contracts for object shapes, enabling type checking and IntelliSense.

Control Flow

Conditional Statements

Control flow uses if, else if, and else. The ternary operator and switch statements are also supported.

Loops

for, for...of, for...in, and while loops handle iteration. Array methods like forEach, map, and filter provide functional alternatives.

Functions

Functions can be typed with parameter and return type annotations. They support default parameters, rest parameters, and overloads. Arrow functions maintain lexical this.

Classes and Object-Oriented Programming

TypeScript enhances JavaScript classes with access modifiers (public, private, protected), abstract classes, and interfaces. It supports inheritance, polymorphism, and generics.

Error Handling

Exception handling uses try, catch, and finally. Custom error classes can extend the built-in Error class.

Modules and Namespaces

Code organization uses ES6 modules (import/export) and namespaces for grouping related code.

Generics

Generics enable reusable components that work with multiple types, providing type safety and flexibility.

Decorators

Decorators are experimental features for meta-programming, allowing modification of classes, methods, and properties at design time.

Integration with JavaScript

TypeScript compiles to JavaScript, supporting various module systems and targeting different ECMAScript versions.

Best Practices

Use strict type checking, avoid any, and leverage interfaces for contracts. Follow naming conventions and use tools like ESLint for code quality.

Testing

Testing frameworks like Jest work seamlessly with TypeScript. Type definitions for test libraries ensure type safety.

Performance Optimization

TypeScript's static analysis helps catch errors early. Compiled output is optimized JavaScript.

Deployment

TypeScript integrates with build tools like Webpack and Babel for compilation and bundling.

Resources and References

Troubleshooting

Common issues include type errors, compilation failures, and integration with JavaScript libraries. Use tsc for compilation and debugging.

Development Setup

Install TypeScript globally or per-project. Configure tsconfig.json for compilation settings. Use IDEs with TypeScript support for better development experience.