Unable to use console log in shorthand arrow function while working with Typescript

Question

Unable to use console log in shorthand arrow function while working with Typescript

When debugging an arrow function in JavaScript, you can write it like this:

const sum = (a, b) => console.log(a, b) || a + b;

This code will first log a and b to the console and then return the actual result of the function. However, when using TypeScript, an error may occur stating that console.log cannot be tested for truthiness:

An expression of type 'void' cannot be tested for truthiness

While this error seems valid, this method is a handy trick for debugging arrow functions, and I would prefer not having to add curly braces to every arrow function if possible.

Even though the console log is temporary, is there any way to make TypeScript accept this pattern without using @ts-ignore?

javascript typescript

Answer 1

Answer №1

Transform the following code to utilize the comma operator:

const printer = (x, y) => (console.log(x, y), x * y);

Answer 2

Transform the following code to utilize the comma operator:

const printer = (x, y) => (console.log(x, y), x * y);

Answer 3

Answer №2

To resolve this issue, you can convert the console.log expression to a boolean.

Here is an example:

const sum = (a, b) => Boolean(console.log(a, b)) || a + b;

By converting the console.log output to boolean, it will always result in false, making sure the subsequent expressions are executed as expected.

Answer 4

To resolve this issue, you can convert the console.log expression to a boolean.

Here is an example:

const sum = (a, b) => Boolean(console.log(a, b)) || a + b;

By converting the console.log output to boolean, it will always result in false, making sure the subsequent expressions are executed as expected.

Answer 5

Answer №3

If you want to customize the behavior of the console type, you can do so by declaring it with your desired modifications. This way, you only need to make the adjustments once instead of changing every call to console.log:

declare const console = {
    log: (...args: unknown[]) => undefined,
    // additional customizations
};

const sum = (a: number, b: number) => console.log(a, b) || 'foo';
const another = (a: number, b: number) => console.log(a, b) || 'bar';

Answer 6

If you want to customize the behavior of the console type, you can do so by declaring it with your desired modifications. This way, you only need to make the adjustments once instead of changing every call to console.log:

declare const console = {
    log: (...args: unknown[]) => undefined,
    // additional customizations
};

const sum = (a: number, b: number) => console.log(a, b) || 'foo';
const another = (a: number, b: number) => console.log(a, b) || 'bar';

Answer 7

Answer №4

This is my preferred approach:

const addition = (x, y) => x + y && alert(x, y);

I hope this suggestion works for you! :)

Answer 8

This is my preferred approach:

const addition = (x, y) => x + y && alert(x, y);

I hope this suggestion works for you! :)

Unable to use console log in shorthand arrow function while working with Typescript

Answer №1

Answer №2

Answer №3

Answer №4

Similar questions

Change element position to relative while scrolling

What factors contribute to 'tslib' having more downloads than 'typecrypt'?

What is the outcome of XmlHttpRequest.responseText?

Include new items in the li tag using JavaScript

What is the best way to pass my session token information between various JavaScript files on the server?

"Learn how to dynamically update a value based on the selected option in a drop-down menu in Angular

You cannot use a relative path when inserting an image tag in React

Perform a check on the state of the slideToggle using an if-else function and provide a report on the slideToggle state

Using JavaScript to display a selection of objects from an array: showcasing x out of x items

When using threejs, the color set for setClearColor is supposed to be white. However, when calling an external HTML file, it unexpectedly renders as

Enhancing Page Content Dynamism: Making Elements Static

What steps should I take to resolve the error: Uncaught SyntaxError: expected expression, received '<'?

Angular keeps FormArray elements' validity up-to-date as new elements are added to the array

The React onChange event fails to trigger

Implement a new feature on a jQuery element

Numerous routers available for enhancing functionality in an Ember application

Create a custom Android home screen widget using JavaScript or another programming language

Passing the IDs of other elements as arguments when invoking a JavaScript function

Ways to EXPAND styled components from imported components

The data in Next.js getStaticProps does not update or refresh as expected