Sep 9, 2021 JavaScript
How to check if a value is an async function in JavaScript

In this Article we will go through how to check if a value is an async function only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const isAsyncFunction = v => Object.prototype.toString.call(v) === '[object AsyncFunction]';

Sep 9, 2021 JavaScript
How to compose functions from left to right in JavaScript

In this Article we will go through how to compose functions from left to right only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

// Compose functions from left to right
const pipe = (...fns) => x => fns.reduce((y, f) => f(y), x);

Sep 9, 2021 JavaScript
How to compose functions in JavaScript

In this Article we will go through how to compose functions only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

// Compose functions from right to left
const compose = (...fns) => x => fns.reduceRight((y, f) => f(y), x);

Sep 9, 2021 JavaScript
How to create a function that accepts a single argument in JavaScript

In this Article we will go through how to create a function that accepts a single argument only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const unary = fn => arg => fn(arg);

Sep 9, 2021 JavaScript
How to count by the properties of an array of objects in JavaScript

In this Article we will go through how to count by the properties of an array of objects only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const countBy = (arr, prop) => arr.reduce((prev, curr) => (prev[curr[prop]] = ++prev[curr[prop]] || 1, prev), {});

Sep 9, 2021 JavaScript
How to delay the evaluation of a function in JavaScript

In this Article we will go through how to delay the evaluation of a function only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

// returns a new version of `fn` that returns values as lazy evaluable
const thunkfy = fn => (...args) => () => fn(...args);

Sep 9, 2021 JavaScript
How to curry a function in JavaScript

In this Article we will go through how to curry a function only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const curry = (fn, ...args) => fn.length <= args.length ? fn(...args) : curry.bind(null, fn, ...args);

Sep 9, 2021 JavaScript
How to execute a function once in JavaScript

In this Article we will go through how to execute a function once only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const once = fn => ((ran = false) => () => ran ? fn : (ran = !ran, fn = fn()))();

Sep 9, 2021 JavaScript
How to remove falsy values from array in JavaScript

In this Article we will go through how to remove falsy values from array only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const removeFalsy = arr => arr.filter(Boolean);

Sep 9, 2021 JavaScript
How to flip the arguments of a function in JavaScript

In this Article we will go through how to flip the arguments of a function only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

// Reverse the order of arguments
const flip = fn => (...args) => fn(...args.reverse());

// For binary functions
const flip = fn => (b, a) => fn(a, b);