<html>
<head>
<script type=‘text/javascript‘>
function test(str){
var tc = document.getElementById("mytextarea");
var tclen = tc.value.length;
tc.focus();
if(typeof document.selection != "undefined")
{
document.selection.createRange().text = str;
}
else
{
tc.value = tc.value.substr(0,tc.selectionStart)+str+tc.value.substring(tc.selectionStart,tclen);
}
}
</script>
</head>
<body>
<textarea rows=5 name=s1 cols=27 id="mytextarea">目的通过点击页面上的按钮button 在textarea中的光标停留处插上文字 </textarea>
<input type=button onclick="test(‘tt‘)" />
</body>
</html>
转：http://blog.csdn.net/xyzqiang/article/details/7003575
原文：http://www.cnblogs.com/casum/p/4655670.html