What is the method to retrieve the 'arguments' in a TypeScript function?

Question

What is the method to retrieve the 'arguments' in a TypeScript function?

I am working on a function that accepts a single argument, named options. Even though I typically prefer using named arguments instead of the options style, it is currently a requirement. The TypeScript documentation provides a specific type for the items within the options object.

const doThing = async ({
  query = null
}: {
  query?: string;
}) => {
  var options = Array.from(arguments)[0]
};

When attempting to use this function, an error occurs:

Cannot find name 'arguments'.ts(2304)

This issue confuses me since arguments should be present in all JavaScript functions.

Is there a way to utilize the arguments object in a TypeScript function?

Purpose of My Task:

To utilize a solitary options argument
To enforce typings and set default values for the data inside
To access the options argument by its given name

typescript

Answer 1

Answer №1

It has been pointed out in previous comments that arrow functions do not have the reserved arguments variable.

However, you can still achieve type safety, a single named argument, and default values by breaking down these requirements into separate statements. This approach not only enhances readability but also improves code comprehension:

interface Options {
    query: string | null;
}

const defaultOptions: Options = {
    query: null,
}

const performTask = async (options: Partial<Options>) => {
    const completeOptions: Options = Object.assign({}, defaultOptions, options);
};

In addition, the Options interface now defines the structure required within the function body.

Furthermore, you can pass a partial set of options without needing to explicitly specify all properties twice inline. Previously, defining default values was done at the value level -- { query = null }, while specifying types and optional keys was handled at the type level -- { query?: string; }. The introduction of the Partial type now handles the optional aspect.

Answer 2

It has been pointed out in previous comments that arrow functions do not have the reserved arguments variable.

However, you can still achieve type safety, a single named argument, and default values by breaking down these requirements into separate statements. This approach not only enhances readability but also improves code comprehension:

interface Options {
    query: string | null;
}

const defaultOptions: Options = {
    query: null,
}

const performTask = async (options: Partial<Options>) => {
    const completeOptions: Options = Object.assign({}, defaultOptions, options);
};

In addition, the Options interface now defines the structure required within the function body.

Furthermore, you can pass a partial set of options without needing to explicitly specify all properties twice inline. Previously, defining default values was done at the value level -- { query = null }, while specifying types and optional keys was handled at the type level -- { query?: string; }. The introduction of the Partial type now handles the optional aspect.

Answer 3

Answer №2

If you're searching for a way to achieve certain functionality, consider using function overloads. This approach allows:

Creating a function with a single parameter.
Specifying different types within the type system.
Adapting the function's behavior based on the type of input received (although this may contradict the OOP principle of Single Responsibility).

To implement function overloads, your code could resemble the following:

function doThingFunc(arg: { query: string, somthingElse?: string }): void;
function doThingFunc(arg: string): void
function doThingFunc(arg: any): void {
  if (typeof arg === 'object') {
    console.log(arg.query);
  }
  if (typeof arg === 'string') {
    console.log(arg);
  }
}
const doThing = doThingFunc;


doThing('some query');
doThing({ query: 'some query', somthingElse: 'something else' });

Keep in mind that by using this approach, you might lose the this binding available with arrow functions when used within an object. Additional details can be found here: https://www.typescriptlang.org/docs/handbook/functions.html

Answer 4

If you're searching for a way to achieve certain functionality, consider using function overloads. This approach allows:

Creating a function with a single parameter.
Specifying different types within the type system.
Adapting the function's behavior based on the type of input received (although this may contradict the OOP principle of Single Responsibility).

To implement function overloads, your code could resemble the following:

function doThingFunc(arg: { query: string, somthingElse?: string }): void;
function doThingFunc(arg: string): void
function doThingFunc(arg: any): void {
  if (typeof arg === 'object') {
    console.log(arg.query);
  }
  if (typeof arg === 'string') {
    console.log(arg);
  }
}
const doThing = doThingFunc;


doThing('some query');
doThing({ query: 'some query', somthingElse: 'something else' });

Keep in mind that by using this approach, you might lose the this binding available with arrow functions when used within an object. Additional details can be found here: https://www.typescriptlang.org/docs/handbook/functions.html

What is the method to retrieve the 'arguments' in a TypeScript function?

Purpose of My Task:

Answer №1

Answer №2

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