效果如图；解决输入时拼音长度也算字符串长度的问题。
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><title>Document</title></head><body>还可以输入<span id="word">10</span>个字<br /><textarea id="txt" maxlength="10"></textarea></body></html><script language="javascript" type="text/javascript">var txt = document.getElementById("txt");var txtNum = document.getElementById("word");var maxlength = 10;var sw = false; //定义关闭的开关txt.addEventListener("keyup", function () {if (sw == false) {countTxt();}});//ompositionstart在输入中文或者语音等需要等待一连串的输入的操作之前触发txt.addEventListener("compositionstart", function () {sw = true;});//compositionend在输入中文或者语音等完毕或取消时触发txt.addEventListener("compositionend", function () {sw = false;countTxt();});//这两个属性有点类似于“开关”，如：开始输入拼音时开关打开，不再改变监测得到的长度数值。用拼音完整输入一个或是一串文字后，开关关闭，此时得到监测的数值长度。function countTxt() { //计数函数if (sw == false) { //只有开关关闭时，才赋值txtNum.textContent = maxlength - txt.value.length;}}</script>
