How to check if a string contains only letters in JavaScript

In this Article we will go through how to check if a string contains only letters 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 isAlpha = str => /^[A-Z]+$/i.test(str);

isAlpha('helloworld');          // true
isAlpha('HelloWorld');          // true
isAlpha('hello world');         // false
isAlpha('0123456789');          // false