How to use the generic parameters inside a function declaration in typescript, when creating function expression

How to Use Generic Parameters Inside a Function Declaration in TypeScript, When Creating Function Expression

When working with TypeScript, you may come across scenarios where you need to use generic parameters inside a function declaration, especially when creating function expressions. In this blog post, we will explore different solutions to this problem.

Solution 1: Using Inline Generic Parameters

One way to use generic parameters inside a function declaration is to define them inline when creating the function expression. Here’s an example:

const myFunction = (param: T): T => {
  // Function body
  return param;
};

// Usage
const result = myFunction("Hello");
console.log(result); // Output: Hello

In the above example, we define the generic parameter T inline when creating the myFunction function expression. We can then use T as the type for the param parameter and also as the return type of the function.

Solution 2: Using Generic Parameters in Function Signature

Another way to use generic parameters inside a function declaration is to define them in the function signature itself. Here’s an example:

type MyFunction = (param: T) => T;

const myFunction: MyFunction = (param) => {
  // Function body
  return param;
};

// Usage
const result = myFunction("Hello");
console.log(result); // Output: Hello

In this example, we define a type MyFunction that represents a function with a generic parameter T. We then use this type to declare the myFunction variable, specifying string as the type argument for T. The function expression assigned to myFunction can now use T as the type for the param parameter and the return type of the function.

Conclusion

Using generic parameters inside a function declaration in TypeScript, especially when creating function expressions, can be achieved through inline generic parameters or by defining generic parameters in the function signature. Both approaches provide flexibility and type safety when working with generic functions.

Feel free to experiment with these solutions in your TypeScript projects and adapt them to your specific use cases. Happy coding!