What Is TypeScript?

TypeScript adds a type system on top of JavaScript. You write TypeScript, the compiler checks your types, and the output is plain JavaScript that runs anywhere JavaScript runs.

Why teams use TypeScript:

• Bugs caught at compile time instead of runtime
• Autocomplete and IDE support become dramatically better
• Refactoring is safer — the compiler tells you what breaks
• API contracts are enforced in code, not just in docs

Basic example:

// JavaScript — no error until runtime
function greet(name) {
  return name.toUpperCase();
}
greet(42); // crashes at runtime

// TypeScript — error at compile time
function greet(name: string) {
  return name.toUpperCase();
}
greet(42); // Error: Argument of type 'number' is not assignable to 'string'

TypeScript in SaaS development: Every project I build is TypeScript from the first commit. In a multi-tenant SaaS, typed database schemas, typed API responses, and typed component props prevent an entire class of bugs before they reach production.

Should you use TypeScript for your MVP? Yes. The initial setup cost is less than one bug it prevents.