TypeScript tutorialLesson 34Free preview

TS Declaration Merging

This lesson is part of TypeScript · All levels

Summary

Declaration merging occurs when two declarations of the same name combine the compiler into one definition. Two interfaces with the same name will merge, while two alias types with the same name will cause error. This pattern is also used for overloading and completing class declarations.

Key points

Two interfaces are the same.
Type alias must not be duplicated
Overload is a form of merging on functions

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