Programming with Types

Appendix B. TypeScript cheat sheet

This cheat sheet is not exhaustive. It covers the TypeScript syntax subset used in this book. For a full TypeScript reference, see http://www.typescriptlang.org/docs.

Table B.1. Primitive types

Type	Description
boolean	Can be true or false.
number	64-bit floating-point number.
string	UTF-16 Unicode string.
void	Type used as return type for functions that don’t return meaningful values.
undefined	Can be only undefined. Represents, for example, a variable that was declared but not initialized.
null	Can be only null.
object	Represents an object or nonprimitive type.
unknown	Can represent any value. Type-safe, so it isn’t implicitly converted to another type.
Any	Bypasses type checking. ...