In typescript, we can utilize index types to perform operations on specific properties:
interface Sample {
title: string;
creationDate: Date;
}
function manipulateProperty<T, K extends keyof T>(obj: T, propName: K): void {
obj[propName]; // execute action, obj[propName] has the type T[K]
}
var sampleObj = { title: "abc", creationDate: new Date() };
manipulateProperty(sampleObj, "title");
Question:
How can we impose a generic constraint that restricts certain property names to only accept specific types? Are there any possible ways to achieve this?
// Generic constraint on T[K]? T[K] should exclusively be of type Date
function manipulateDATEProperty<T, K extends keyof T>(obj: T, propName: K): void {
obj[propName];
}
// The following code should not compile,
// as it should only accept the name of the property "creationDate" which is of type date
manipulateDATEProperty(sampleObj, "title");