Web Front-endJS TutorialSample code sharing for implementing the function of counting remaining words in a multi-line text box using js
本文主要介绍了js实现多行文本框统计剩余字数功能的相关知识。具有很好的参考价值。下面跟着小编一起来看下吧
效果图：
代码如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>js统计文本框剩余字数</title>
<style type="text/css">
#area{
width: 300px;
height: 300px;
resize:none;
}
</style>
</head>
<body>
<textarea autofocus id="area" onkeydown="sy()" maxlength="10" placeholder="只能输入十个字"></textarea>
<!--
resize:none 多行文本框不可以拖动
onkeypress="sy()"键盘按住或点击时调用方法
maxlength="10"定义最大宽度
placeholder="只能输入十个字" 定义默认提示
autofocus 定义自动获得焦点
-->
<span>你还可以输入:<strong id="span" >10</strong>个字</span>
<input type="button" value="统计" onclick="fun();">
<p id="p"></p>
<script type="text/javascript">
function sy() {
var num=document.getElementById("area").value.length;
//console.log(num);
var sheng=10-num;
if(sheng==0){
//变颜色为红色
console.log(sheng);
document.getElementById("span").style.color="#ff0000";
}else{
//变颜色为黑色
document.getElementById("span").style.color="#000000";
}
document.getElementById("span").innerHTML=sheng;
}
function fun(){
var txt=document.getElementById("area").value;
//这么写的意思是申请abc三个值都为0
var a=b=c=0;
for(var i=0;i<txt.length;i++){
var ch=txt.charAt(i);
if(ch>="a"&&ch<="z"){
a++;
}else if(ch>="A"&&ch<="Z"){
b++;
}else if(ch>="0"&&ch<="9"){
c++;
}
}
//abc中分别统计了小写字母、大写字母、数字的个数
document.getElementById("p").innerHTML="大写字母有"+b+"个，小写字母有"+a+"个，数字有"+c+"个";
}
</script>
</body>
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