Comparison
JavaScript and TypeScript
TypeScript builds on JavaScript by adding a type system and a checking workflow.
At a glance
- JavaScript
- Runtime programming language
- TypeScript
- JavaScript with static type checking
Overview
TypeScript builds on JavaScript by adding a type system and a checking workflow. JavaScript provides runtime language behavior, while TypeScript can report incompatible operations before execution. The choice concerns development constraints and tooling as well as the code that eventually runs.
What differs
TypeScript records and infers types so a checker can analyze a program. JavaScript execution still underlies the resulting behavior, and understanding JavaScript remains necessary for interpreting what the program does.
Choose by the task
A type layer can help maintain explicit interfaces and catch mismatches as a project evolves. Evaluate that benefit alongside the project's existing tooling, contributors, and integration requirements.
Common confusion
A successful type check does not validate arbitrary external data or prove application logic. Keep runtime validation and behavioral tests where those are required by the application's contract.
Sources and review
MOOR's explanatory text is supported by the following source links.
- JavaScript introduction — MDN Web Docs
- TypeScript and JavaScript — TypeScript