TypeScript vs JavaScript: Understanding the Key Differences

TypeScript is a superset of JavaScript that introduces static typing to the language. While JavaScript is dynamic, flexible, and widely used for web development, TypeScript adds optional type annotations and advanced tooling, making large-scale application development more robust and maintainable.

Key Differences Between TypeScript and JavaScript

• Typing System:
  • JavaScript is dynamically typed (types are determined at runtime).
  • TypeScript is statically typed (types are checked during development/compile time).
• Compilation:
  • JavaScript code runs directly in browsers or Node.js.
  • TypeScript code is compiled into plain JavaScript before it can run.
• Tooling Support:
  • TypeScript offers better code autocompletion, error checking, and refactoring in editors due to the type system.
• Optional Features:
  • TypeScript lets you use modern JavaScript features (ES6+), even if the target environment doesn’t support them, through transpilation.

Simple Example

JavaScript

function greet(name) {
    return 'Hello, ' + name;
}

TypeScript

function greet(name: string): string {
    return 'Hello, ' + name;
}

TypeScript's type annotation (name: string) helps catch errors early:

• Calling greet(5) in JavaScript fails only at runtime;
• TypeScript will warn you during development.

Summary

TypeScript improves upon JavaScript by adding static type checking, which helps developers write safer, more maintainable code. You write TypeScript, compile it to JavaScript, and then run it, gaining powerful development benefits along the way.