TypeScript has a feature called index signatures. This is not advised, and you should use the Nested index signature pattern mentioned above. Weak Type Detection in TypeScript December 1, 2017. Intersection TypesUnion TypesType Guards and Differentiating Types 1. Exhaustiveness checkingPolymorphic this typesIndex types 1. With this PR an object literal type is assignable to a type with an index signature if all known properties in the object literal are assignable to that index signature. to help the next dev who looks at the code (which just might happen to be you). Indexable types have an index signature that describes the types that we can use as an index for our object, alongside the return type for the corresponding index. index signature in typescript; index.js:1 Warning: Failed prop type: The prop `expandableRows` is marked as required in `<>` indexable type in ts; init empty object typescript; initialize empty array typescript; injection of generic services in angular; inline scripts encapsulated in