JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="test">One
Two
Three</textarea>

JavaScript

function showLineBreaks(str) {
    return str.replace(/\r/g, "[\\r]").replace(/\n/g, "[\\n]");
}
          
$textarea = $("#test");
alert(showLineBreaks("val(): " + $textarea.val()) + "\n" + "value: " + showLineBreaks($textarea[0].value));