Sep 9, 2021 JavaScript
How to check if an array is subset of other array in JavaScript

In this Article we will go through how to check if an array is subset of other 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:

// Check if `b` is subset of `a`
const isSubset = (a, b) => (new Set(b)).size === (new Set(b.concat(a))).size;

Sep 9, 2021 JavaScript
How to check if an object is a promise in JavaScript

In this Article we will go through how to check if an object is a promise 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 isPromise = obj => !!obj && (typeof obj === 'object' || typeof obj === 'function') && typeof obj.then === 'function';

Sep 9, 2021 JavaScript
How to validate a gregorian date in JavaScript

In this Article we will go through how to validate a gregorian date 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 isValidDate = (m, d, y) => 0 <= m && m <= 11 && 0 < y && y < 32768 && 0 < d && d <= (new Date(y, m, 0)).getDate();

Sep 9, 2021 JavaScript
How to check if a date is a weekend in JavaScript

In this Article we will go through how to check if a date is a weekend 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 isWeekend = (date = new Date()) => date.getDay() % 6 === 0;

Sep 9, 2021 JavaScript
How to check if a given integer is a prime number in JavaScript

In this Article we will go through how to check if a given integer is a prime number 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 isPrime = num => (num > 1) && Array(Math.floor(Math.sqrt(num)) - 1).fill(0).map((_, i) => i + 2).every(i => num % i !== 0);

Sep 9, 2021 JavaScript
How to check if a number is negative in JavaScript

In this Article we will go through how to check if a number is negative 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 isNegative = number => Math.sign(number) === -1;

Sep 9, 2021 JavaScript
How to check if a string contains upper case characters in JavaScript

In this Article we will go through how to check if a string contains upper case characters 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 containsUpperCase = str => str !== str.toLowerCase();

Sep 9, 2021 JavaScript
How to check if a string is lower case in JavaScript

In this Article we will go through how to check if a string is lower case 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 isLowerCase = str => str === str.toLowerCase();

Sep 9, 2021 JavaScript
How to check if a value is a plain object in JavaScript

In this Article we will go through how to check if a value is a plain object 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 isPlainObject = v => (!!v && typeof v === 'object' && (v.__proto__ === null || v.__proto__ === Object.prototype));

Sep 9, 2021 JavaScript
How to check if a value is a regular expression in JavaScript

In this Article we will go through how to check if a value is a regular expression 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 isRegExp = value => Object.prototype.toString.call(value) === '[object RegExp]';