These utilities allow developers to transform string types for specific needs, such as ensuring event names are consistently uppercase or converting between camelCase and PascalCase. Practical Applications
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 TypeScript 4.1 beta brings template literal types
TypeScript 4.1 also introduced to support these new capabilities: Uppercase Lowercase Capitalize Uncapitalize These utilities allow developers to transform string types
: Combining a literal type with a template produces a single, specific string type. Template literal types bring the syntax of JavaScript's
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
: New as clauses allow developers to transform property names when creating new object types. For example, you can take an existing interface and generate a new one with "changed" suffixes for event handling.
: 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