方法一：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<textarea name="" id="txt" cols="30" rows="10"></textarea>
<input type="button" id="btn" value="点击按钮">
<div id="desc"></div>
</body>
<script>
var txt = document.getElementById(‘txt‘)
var btn = document.getElementById(‘btn‘)
var desc = document.getElementById(‘desc‘)
btn.onclick = function () {
var val = txt.value
val = val.replace(/\r\n/g, ‘<br/>‘); //IE9、FF、chrome
val = val.replace(/\n/g, ‘<br/>‘); //IE7-8
val = val.replace(/\s/g, ‘ ‘); //空格处理
desc.innerHTML = val;
}
</script>
</html>
方法二:
原文：https://www.cnblogs.com/zmh-980509/p/11622119.html