How can we define and put into action a function in TypeScript that incorporates certain properties?

I have a vision of creating a message feature that can be invoked directly with overloading capabilities. I also wish to incorporate other function calls within this message feature, such as message.confirm(). Achieving this in TypeScript seems challenging when it comes to writing type descriptions and implementing them simultaneously.

My attempts at defining a class showed that the use of the new keyword is necessary for calling it. Trying to define a function directly also proved insufficient in meeting the required function properties. This process requires careful steps to fully accomplish.

As an example, consider the following class definition which prompts the need to use new for invocation:

class message {
    message(msg: string): any
    message(msg: string, type: string): any
    message(msg: string, type?: string){

    }

    static confirm(){

    }
}

message("123")

Another hurdle I face is with the following definition:

type Message = {
    message(msg: string): any
    message(msg: string, type: string): any
    confirm(): any
}

const message: Message = function message (msg: string, type?: string)
    {
    }

message.confirm = function(){}

My ultimate question remains - How can I effectively define and implement the message function?

Answer №1

If you desire to treat a Message as a function, it is recommended to use call signatures instead of methods named message():

type Message = {
  (msg: string): any // <-- call signature, not method
  (msg: string, type: string): any // <-- call signature, not method
  confirm(): any
}

This will allow your example code to start functioning properly, thanks to the integration of property declarations on functions:

const message: Message = function message(msg: string, type?: string) {
}

message.confirm = function () { }

Try out the code here

Answer №2

Here is a step-by-step guide on how to define and execute the message function based on your specific requirements.

interface Message {
  (msg: string): any;
  (msg: string, type: string): any;
  confirm(): any;
}

const myMessage: Message = function(msg: string, type?: string) {
  if(type) {
    console.log(`Message: ${msg}, Type: ${type}`);
  } else {
    console.log(`Message: ${msg}`);
  }
};

myMessage.confirm = function() {
  console.log('Confirmation message');
};

// Example Usage
myMessage('Greetings!');
myMessage('Greetings!', 'announcement');
myMessage.confirm(); // Call the confirm method

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