how to use the hasownproperty function from the date-fns library in typescript

To use the hasOwnProperty function from the date-fns library in Typescript, we need to first install the library using a package manager like npm:

index.ts
npm install date-fns
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After installing, we can import the function as follows:

index.ts
import { hasOwnProperty } from 'date-fns';
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Next, we can use the function in our code while ensuring type safety. Here's an example of using hasOwnProperty to check if an object has a getFullYear property:

index.ts
interface MyDate {
  getFullYear(): number;
  // other properties and methods
}

const myDate: MyDate = { getFullYear: () => 2021, /* other properties */ };

if (hasOwnProperty(myDate, 'getFullYear')) {
  console.log(myDate.getFullYear());
}
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In the above example, we define an interface MyDate that our myDate object implements. We then use hasOwnProperty to check if myDate has a getFullYear property before calling it to log the year.

Note that we can also add type annotations for the parameters of hasOwnProperty to ensure type safety:

index.ts
if (hasOwnProperty<MyDate, keyof MyDate>(myDate, 'getFullYear')) {
  console.log(myDate.getFullYear());
}
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Here, we add type annotations using angle brackets to specify the type of the object and the key to check. This ensures that we can only check for valid keys of MyDate.