键盘按下抬起简单应用

来源：互联网发布：零起点学算法编辑：程序博客网时间：2024/05/18 00:52

<!DOCTYPE html><html><head><title>ZzhJs2.html</title><meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="this is my page"><meta http-equiv="content-type" content="text/html; charset=UTF-8"><!--<link rel="stylesheet" type="text/css" href="./styles.css">--><script type="text/javascript">var a = document.getElementById("area");//count方法 作用 检测id="area"中字符长度    如果大于100显示红色  否则的显示绿色 function count() {if (a.value.length > 100) {a.value = a.value.substring(0, 100);}var num = a.value.length;var sheng = 100 - num;var s = document.getElementById("span");if (sheng == 0) {s.style.color = "#ff0000";} else {s.style.color = "#00ff00";}s.innerHTML = "还剩(" + sheng + ")个字";}//fun方法统计id=area区域总大写 小写 数字分别的个数function fun() {var str = a.value;var num1 = num2 = num3 = 0;for ( var i = 0; i < str.length; i++) {var ch = str.charAt(i)if (ch >= 'A' && ch <= 'Z') {num1++;} else if (ch >= 'a' && ch <= 'z') {num2++;} else if (ch >= '0' && ch <= '9') {num3++;}}document.getElementById("div").innerHTML = "大写字母:" + num1 + "小写字母:"+ num2 + "数字:" + num3;}</script></head><body><!-- 当键盘中某一个键抬起的时候就运行count方法      键盘按下和抬起分别是onkeydown和onkeyup --><textarea rows="5" cols="20" id="area" onkeydown="count();"></textarea><br><span id="span">还剩(100)个字</span><input type="button" value="统计" onclick="fun();"><div id="div"></div></body></html>

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键盘按下抬起 简单应用

键盘按下抬起简单应用