How to remove duplicate lines of a text document in JavaScript

In this Article we will go through how to remove duplicate lines of a text document 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 removeDuplicateLines = str => Array.from(new Set(str.split(/\r?\n/))).join('\n');

removeDuplicateLines(`one
three
two
three
one
four`);

/* Output */
/*
one
three
two
four
*/