<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
textarea{font-size:1em; width:500px; height:100px;}
</style>
</head>
<body>
<textarea id="target"></textarea>
<p><button id="btn">插入话题</button></p>
</body>
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.js"></script>
<script>
var $ = function(id){
return document.getElementById(id);
};
$("btn").onclick = function(){
var con = "请在这里输入自定义话题";
//转载文字
$("target").innerHTML += "#"+con+"#";
var l = $("target").innerHTML.length;
//创建选择区域
if($("target").createTextRange){//IE浏览器
var range = $("target").createTextRange();
range.moveEnd("character",-l)
//range.moveStart("character",-l)
range.moveEnd("character",l-1);
range.moveStart("character", l-1-con.length);
range.select();
}else{
$("target").setSelectionRange(l-1-con.length,l-1);
$("target").focus();
}
};
</script>
</html>
