JSFiddle - React, Tailwind, and code Playground

JavaScript

window.onload = function(){
    var testText = "line1\n\nline2\n\n\n\line3\nline4";
    document.write(testText.split(/\n/).join("(newline)"));  
    document.write("<hr/>");    
    document.write(testText.split("\n").join("(newline)"));  
};