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<head>
<title>Insert Text into TextBox at Cursor Position by Javascript</title>
<script type="text/javascript">
var cursPos; // 窗口全局变量，保存目标 TextBox 的最后一次活动光标位置
function insertText() {
var txt1 = document.getElementById("Text1");
var txt2 = document.getElementById("Text2");
//debugger;
if(!cursPos) TraceCursorPosition(txt2); // 获取光标位置
txt2.value = txt2.value.slice(0, cursPos.start) +
txt1.value + txt2.value.slice(cursPos.end)
}
// 跟踪光标位置
function TraceCursorPosition(obj)
{
//debugger;
cursPos = $CursorPosition(obj);
}
// 返回光标所在位置
/**//*
* source: http://blog.csdn.net/liujin4049/archive/2006/09/19/1244065.aspx
* source: http://www.devdao.com
* acknowledges for Marshall
* example:
* var myTextBox = document.getElementById("MyTextBoxID");
* var cursPos = $CursorPosition(myTextBox);
* alert(cursPos.item[0] + " " + cursPos.item[1]);
* // OR
* alert(cursPos.start + " " + cursPos.end);
*/
function $CursorPosition(textBox){
var start = 0, end = 0;
//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 ++;
}
}
}
//return [start, end]; // 包括选中区域的起始位置
// modified to return as Object
return {"start": start, "end": end, "item": [start, end]};
}
</script>
</head>
<body>
input :<input id="Text1" type="text" /><input id="Button1" type="button" value="Insert" onclick="insertText()" /><br />
output:<textarea id="Text2" cols="40" rows="10" onkeydown="TraceCursorPosition(this)" onkeypress="TraceCursorPosition(this)" onfocus="TraceCursorPosition(this)" onselect="TraceCursorPosition(this)" onmouseover="TraceCursorPosition(this)" onmousedown="TraceCursorPosition(this)">hello world!</textarea><br />
</body>
</html>