: They enable the creation of type-safe dot notation for accessing nested object properties and parsing router parameters (like :userId ) to ensure they match expected formats.
Example : Combining type Color = "red" | "blue" and type Size = "small" | "large" into $Color-$Size results in four distinct types: "red-small" , "red-large" , "blue-small" , and "blue-large" . Core Features and Utility Types
The introduction of template literal types solved several long-standing type-safety challenges: TypeScript 4.1 beta brings template literal types
: Developers can now enforce specific patterns, such as validating IPv4 addresses (e.g., $number.$number.$number.$number ) directly at the type level.
: When combined with conditional types and the infer keyword, template literal types can act as a simple parser, breaking down complex strings into their constituent parts for deep type inspection. Conclusion Documentation - Template Literal Types - TypeScript : They enable the creation of type-safe dot
TypeScript 4.1 also introduced to support these new capabilities: Uppercase Lowercase Capitalize Uncapitalize
: Combining a literal type with a template produces a single, specific string type. : When combined with conditional types and the
Template literal types bring the syntax of JavaScript's template strings (using backticks and ${} ) into type positions. While standard string literal types define a variable as holding a specific, fixed string, template literal types allow for the of new string types by concatenating existing ones. Key Syntax and Composition