给 Textarea中选定的文字前后加上标签,具体做法如下:(经测试Firefox和IE中全部通过)

<html>
<head>
<title>TEST</title>
<style>
body,td{
font-family: verdana, arial, helvetica, sans-serif;
font-size: 12px;
}
</style>
<script type="text/javascript">
var start=0;
var end=0;
function add(flg1,flg2){
var textarea_str = document.getElementById("ta");
var pre = textarea_str.value.substr(0, start);
var post = textarea_str.value.substr(end);
var center = textarea_str.value.substr(start,end-start);
textarea_str.value = pre + flg1 +center+ flg2+ post;
// Firefox
if(typeof(textarea_str.selectionStart) == "number"){
textarea_str.setSelectionRange(start+flg1.length,start+flg1.length);
textarea_str.focus();
}
// IE
if(document.selection){
var tempMouseFocusPos = start;
for (var i = 0; i <= start; i ++){
if (textarea_str.value.charAt(i) == ' ')
tempMouseFocusPos--;
}
if(start == end) {
textarea_str.select();
var rangeIE = document.selection.createRange();
rangeIE.move('character',tempMouseFocusPos+flg1.length);
rangeIE.select();
} else {
var rangeIE = document.selection.createRange();
rangeIE.move('character',tempMouseFocusPos+flg1.length);
rangeIE.select();
}
}
}
function savePos(textarea_str){
if(typeof(textarea_str.selectionStart) == "number"){
start = textarea_str.selectionStart;
end = textarea_str.selectionEnd;
}
else if(document.selection){
var range = document.selection.createRange();
if(range.parentElement().id == textarea_str.id){
// create a selection of the whole textarea
var range_all = document.body.createTextRange();
range_all.moveToElementText(textarea_str);
for (start=0; range_all.compareEndPoints("StartToStart", range) < 0; start++)
range_all.moveStart('character', 1);
for (var i = 0; i <= start; i ++){
if (textarea_str.value.charAt(i) == ' ')
start++;
}
var range_all = document.body.createTextRange();
range_all.moveToElementText(textarea_str);
for (end = 0; range_all.compareEndPoints('StartToEnd', range) < 0; end ++)
range_all.moveStart('character', 1);
for (var i = 0; i <= end; i ++){
if (textarea_str.value.charAt(i) == ' ')
end ++;
}
}
}
}
</script>
</head>
<body>
<form action="a.cgi">
<table border="1" cellspacing="0" cellpadding="0">
<tr>
<td colspan="2">
<textarea id="ta" onKeydown="savePos(this)"
onKeyup="savePos(this)"
onmousedown="savePos(this)"
onmouseup="savePos(this)"
onfocus="savePos(this)"
rows="14" cols="50"></textarea>
</td>
</tr>
<tr>
<td><input type="button" onClick="add('[&BOL]','[/&BOL]')" value="Add [&BOL][/&BOL]"/></td>
</tr>
</table>
</form>
</body>
</html>































































































