TypeScript vs JavaScript

TypeScript and JavaScript are both widely used for web development, but they serve different purposes. TypeScript is a superset of JavaScript, which means it includes all features of JavaScript but adds additional functionality, like static typing.

 

Key Differences Between TypeScript and JavaScript

Static Typing

• TypeScript: TypeScript uses static typing, meaning you must define the types of variables, function parameters, and return values before runtime. This helps catch errors at compile-time.
• JavaScript: JavaScript is dynamically typed, meaning types are assigned at runtime and can lead to errors that only appear during execution.

Compilation

• TypeScript: TypeScript code needs to be compiled into JavaScript before it can run in the browser or Node.js.
• JavaScript: JavaScript runs directly in the browser or Node.js, without needing any compilation.

Advanced Features

• TypeScript: TypeScript introduces advanced features like interfaces, generics, enums, and decorators, providing better support for large-scale applications.
• JavaScript: JavaScript, though powerful, lacks these advanced features and relies more on runtime checks.

Backward Compatibility

• TypeScript: TypeScript is backward compatible with JavaScript, meaning any valid JavaScript code is also valid TypeScript code.
• JavaScript: JavaScript code does not need any compilation or additional steps before execution.

Development Experience

• TypeScript: TypeScript offers better tooling, such as code completion, static analysis, and inline documentation, which leads to a smoother development experience, especially for larger codebases.
• JavaScript: JavaScript is more flexible, but this can sometimes lead to difficulty when managing larger projects.

 

Code Comparison

JavaScript Example

function add(a, b) {
  return a + b;
}
console.log(add(5, "10")); // Output: "510"

TypeScript Example

function add(a: number, b: number): number {
  return a + b;
}
// Error during compilation if types mismatch:
// Argument of type 'string' is not assignable to parameter of type 'number'.
console.log(add(5, 10)); // Output: 15

 

Summary

TypeScript enhances JavaScript by adding static typing and other advanced features, making it ideal for large-scale projects where type safety and maintainability are key. JavaScript remains the go-to choice for simpler projects or those where rapid prototyping is needed.