[解決済み] camelCase」を「キャメルケース」に変換するには？

(function() {

  const textbox = document.querySelector('#textbox')
  const result = document.querySelector('#result')
  function split() {
      result.innerText = textbox.value
        // insert a space before all caps
        .replace(/([A-Z])/g, ' $1')
        // uppercase the first character
        .replace(/^./, (str) => str.toUpperCase())
    };

  textbox.addEventListener('input', split);
  split();
}());

#result {
  margin-top: 1em;
  padding: .5em;
  background: #eee;
  white-space: pre;
}

<div>
  Text to split
  <input id="textbox" value="thisStringIsGood" />
</div>

<div id="result"></div>