我只是想在文本區域內輸入時計算剩余的字符數。我對 Javascript 很陌生，我寫了這段代碼，但它不起作用，我也不知道為什么。它不算什么。始終顯示 0 / 300。html文件中的代碼：<p>  <textarea name="Inhalt" id="Inhalt" placeholder="Ihre Nachricht..." rows="5" maxlength="300 </textarea> </p>    <div id="the-count"> <span id="current">0</span> <span id="maximum">/ 300</span></div><script src="textarea_count.js"></script>textarea_count.js 中的代碼：$('textarea').onkeyup(function() {var characterCount = $(this).val().length,  current = $('#current'),  maximum = $('#maximum'),  theCount = $('#the-count');current.textContent(characterCount);if (characterCount < 100) {current.css('color', '#666');}if (characterCount > 99 && characterCount < 140) {current.css('color', '#6d5555');}if (characterCount > 139 && characterCount < 200) {current.css('color', '#793535');}if (characterCount > 199 && characterCount < 250) {current.css('color', '#841c1c');}if (characterCount > 249 && characterCount < 299) {current.css('color', '#8f0001');}if (characterCount >= 300) {maximum.css('color', '#8f0001');current.css('color', '#8f0001');theCount.css('font-weight','bold');} else {maximum.css('color','#666');theCount.css('font-weight','normal');}  });*請注意，我從 html 部分刪除了不重要的代碼，因為它與 textarea 無關，只是沒有必要考慮。