Description
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Coding
TypeScript foundations
Build on basic JavaScript with 32 lessons about types, safe functions, structured data, and practical TypeScript projects.
Learn practical TypeScript foundations after basic JavaScript. Check types, handle missing values, and model everyday data.
- 1
Types and values
Use basic type annotations and distinguish type checking from execution.
10 min
- 2
Inference and reassignment
Let TypeScript infer a type and keep later assignments compatible.
10 min
- 3
Typed functions
Describe function parameters and return values.
10 min
- 4
Typed arrays
Keep collections consistent and handle an array that may be empty.
10 min
- 5
Object types and interfaces
Describe the shape of an object and reuse that description.
10 min
- 6
Optional and nullable values
Check missing values instead of assuming that they exist.
10 min
- 7
Unions and narrowing
Handle each allowed kind of value before using its specific operations.
10 min
- 8
Literal unions
Limit a value to a small set of meaningful choices.
10 min
- 9
Readonly data
Prevent accidental writes through a type and create updated copies.
10 min
- 10
Generic functions
Preserve the relationship between an input type and its result.
10 min
- 11
Checking unknown input
Use runtime checks before trusting data that comes from outside typed code.
10 min
- 12
Project: a typed order summary
Combine object types, arrays, functions, and runtime validation in a small project.
10 min