Creating a custom type for accepted arguments in a Typescript method

Question

Creating a custom type for accepted arguments in a Typescript method

Below is the structure of a method I have:

const a = function (...args: any[]) {
  console.log(args);
}

In this function, the type of args is any[]. I am looking to create a specific type for the array of arguments accepted by this method in Typescript. How can I achieve creating a specific type for the arguments accepted by this method? NOTE: The function a can accept various types of arguments such as

a(1, 2, 4, 5, 'asgasg', 124.52, { name: 'sparsh' });

I am aiming to define a specific type for the arguments allowed by the method in Typescript.

javascript typescript typescript-generics

Answer 1

Answer №1

If you need a specialized data type, you can define it yourself:

type myType = string | number

Here's an example of how you can use this custom type in a scenario:

type Person = {
  name: string;
}

type myType = string | number | Person;

function myFunction(...args: myType[]){}

Answer 2

If you need a specialized data type, you can define it yourself:

type myType = string | number

Here's an example of how you can use this custom type in a scenario:

type Person = {
  name: string;
}

type myType = string | number | Person;

function myFunction(...args: myType[]){}

Answer 3

Answer №2

Instead of using any[], consider utilizing unknown[].
By using unknown[], you can pass any type of arguments without disabling type checking for property access. For instance:

const a = function (...args: unknown[]) {
  console.log(args);
// console.log(args[0].toString); //disallowed by type checking 
  if(typeof args[0] === 'number') console.log(args[0].toFixed()) //allowed
}

a(2,3,4,5,6,7,"asds"); //ok

Answer 4

Instead of using any[], consider utilizing unknown[].
By using unknown[], you can pass any type of arguments without disabling type checking for property access. For instance:

const a = function (...args: unknown[]) {
  console.log(args);
// console.log(args[0].toString); //disallowed by type checking 
  if(typeof args[0] === 'number') console.log(args[0].toFixed()) //allowed
}

a(2,3,4,5,6,7,"asds"); //ok

Creating a custom type for accepted arguments in a Typescript method

Answer №1

Answer №2

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