How to use TypeScript Interfaces In Typescript

You can also use TypeScript interface to create a blue print of the return type value of a function which can be later used to assign the return type to the function.

Syntax:

interface interfaceName{}

Example: The below code practically implements the interface to type the return value of the function.

Javascript

interface ReturnValue {
    result: number;
}

function myFunc(): ReturnValue {
    return { result: 10 };
}

const result: ReturnValue = myFunc(); 
console.log("Result:", result.result);

Output:

Result: 10

How to Strongly Type the Return Value of any Function in TypeScript ?

Specifying the return type after a function’s parameters with a colon ensures a consistent return value type. This enhances code reliability by enforcing expected return types. It is a fundamental feature of TypeScript that ensures functions consistently produce values of the specified type. The below methods can be used to achieve this task: