· intermediate
TypeScript
Types that catch mistakes before anyone runs the code. Inference doing most of the work, narrowing that makes checks provable, and why the types disappear the moment the program starts.
Written in house, from the work rather than from a syllabus. Every example is one we would use ourselves, and every quiz question explains why its answer is right.
What you’ll learn
- Explain what the compiler checks, and that nothing is checked at runtime
- Let inference do the work instead of annotating everything
- Model data with unions so invalid combinations cannot be written
- Narrow a union so the compiler proves a check for you
- Write a simple generic without reaching for any
- Validate data at the boundary, where types stop being guarantees
Before you start
- · JavaScript Fundamentals, or equivalent
- · No prior TypeScript