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AI solution for TypeScript puzzle on
4. implement Record<K, V>

type MyRecord<K extends keyof any, V> = {
  [P in K]: V;


  • MyRecord is a generic type that takes two type parameters, K and V.
  • K must be assignable to keyof any to ensure it only accepts valid property keys in TypeScript, i.e., number, string, or symbol.
  • We use a mapped type to create a new type where each property with key of P in K has a value of V. This type is assigned to the variable MyRecord.
  • Finally, we can use MyRecord to create an object with properties that have keys of type K and values of type V.

Note: This implementation ensures that the returned object has only properties with key names that are explicitly typed in K. This means that any attempt to define a property outside the K keys will result in a compilation error.