TypeScript tutorialLesson 33Free preview

TS Index Signatures

This lesson is part of TypeScript · All levels

Summary

Index signature declares a type of value for all keys of a particular type, such that each string becomes a number. This pattern is useful for dictionaries, configurations, or labelled scores. The entire concrete property on the interface must be compatible with the index type.

Key points

Index signature uses [key: type]: typeValue
Can use a string or a number key
All properties must be compatible with the index

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