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在textarea光标指定地方插入内容

2013年03月05日 ⁄ 综合 ⁄ 共 3327字 ⁄ 字号 评论关闭
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!--http://community.csdn.net/Expert/TopicView3.asp?id=5649731-->
<html xmlns="http://www.w3.org/1999/xhtml" >
<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
* 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>

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