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javascript获取textarea光标位置，内容方法(IE, Firefox)

2011-06-29 21:56 846 查看

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="jsCursorDemo._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<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("start").value = start;
document.getElementById("end").value = end;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<table border="1" cellspacing="0" cellpadding="0">
<tr>
<td>
start:
<input type="text" id="start" size="3" />
</td>
<td>
end:
<input type="text" id="end" 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);" onmousemove="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>

</div>
</form>
</body>
</html>

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标签： javascript textbox 光标位置

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