TSadvancedts-evergreen
Template literal types
String types you can compute.
Template literal types apply backtick interpolation at the type level — ` on${Capitalize<E>} ` — letting the compiler build, constrain, and even parse string types from other types instead of treating every string the same.
A greeting type with a literal placeholder
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greet('Ada') returns "Hello, Ada!" and greet('world') returns "Hello, world!" — the same literal shape the Greeting<T> type encodes, so the runtime builder's return type is the template literal type itself, not a loose string.