js获取光标位置例子
<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() {
var textBox = document.getElementById("ta");
var pre = textBox.value.substr(0, start);
var post = textBox.value.substr(end);
textBox.value = pre + document.getElementById("inputtext").value + post;
}
function savePos(textBox) {
//如果是Firefox(1.5)的话，方法很简单
if (typeof (textBox.selectionStart) == "number") {
start = textBox.selectionStart;
end = textBox.selectionEnd;
}
//下面是IE(6.0)的方法，麻烦得很，还要计算上'\n'
else if (document.selection) {
var range = document.selection.createRange();
if (range.parentElement().id == textBox.id) {
// create a selection of the whole textarea
var range_all = document.body.createTextRange();
range_all.moveToElementText(textBox);
//两个range，一个是已经选择的text(range)，一个是整个textarea(range_all)
//range_all.compareEndPoints()比较两个端点，如果range_all比range更往左(further to the left)，则 //返回小于0的值，则range_all往右移一点，直到两个range的start相同。
// calculate selection start point by moving beginning of range_all to beginning of range
for (start = 0; range_all.compareEndPoints("StartToStart",range) < 0; start++){
range_all.moveStart('character', 1);
}
// get number of line breaks from textarea start to selection start and add them to start
// 计算一下\n
for ( var i = 0; i <= start; i++) {
if (textBox.value.charAt(i) == '\n')
start++;
}
// create a selection of the whole textarea
var range_all = document.body.createTextRange();
range_all.moveToElementText(textBox);
// calculate selection end point by moving beginning of range_all to end of range
for (end = 0; range_all.compareEndPoints('StartToEnd', range) < 0; end++)
range_all.moveStart('character', 1);
// get number of line breaks from textarea start to selection end and add them to end
for ( var i = 0; i <= end; i++) {
if (textBox.value.charAt(i) == '\n')
end++;
}
}
}
document.getElementById("startId").value = start;
document.getElementById("endId").value = end;
}
</script>
</head>
<body>
<form action="a.cgi">
<table border="1" cellspacing="0" cellpadding="0">
<tr>
<td>start: <input type="text" id="startId" size="3" /></td>
<td>end: <input type="text" id="endId" size="3" /></td>
</tr>
<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="text" id="inputtext" /></td>
<td><input type="button" onClick="add()" value="Add Text" /></td>
</tr>
</table>
</form>
</body>
</html>
posted on 2013-11-01 13:13 andydaopeng 阅读(351) 评论(0) 编辑 收藏 举报
