JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="ru">
  <head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <title>Pi</title>
  </head>
  <body>
    <h3>Enter a mathematical constant:</h3>
    <textarea class="form-textarea" rows="7" cols="64" name="text" id="text"></textarea><br><br>
    <input type="button" class="form-submit" value="Create" onclick="narezka()"><br><br>
    <strong>Private Key (64):</strong><br>
    <pre...

JavaScript

function narezka() {
	text = $("#text").val().replaceAll(/\s/g, '');
  chunkLength = Math.min(text.length, 64);
  result = "";
  if (chunkLength > 0) {
    for (let i = 0; i <= text.length - chunkLength; i++) {
			result += text.substring(i, i + chunkLength) + "\n";
    }
  }
  result = result.trim();
  $("#result").text(result);
}