javascript擷取textarea游標選擇位置和內容方法(IE, Firefox)

最後更新：2018-12-07 來源：互聯網

上載者：User

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原文：http://blog.csdn.net/liujin4049/archive/2006/09/19/1244065.aspx

在網上用baidu找了很久，找到的都是IE的方法，Firefox都不能用。而且很多要用到<textarea>.focus()方法，用起來很不方便。
後來轉用Google，搜了下"textarea cursor"，第一個就有好方法。我根據最後一個傢伙的comments，寫了一個sample，應該還是挺好用的。
原文地址：http://weblogs.asp.net/skillet/archive/2005/03/24/395838.aspx

<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)的話，方法很簡單
        if(typeof(textBox.selectionStart) == "number"){
            start = textBox.selectionStart;
            end = textBox.selectionEnd;
        }
        //下面是IE(6.0)的方法，麻煩得很，還要計算上'\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);
                //兩個range，一個是已經選擇的text(range)，一個是整個textarea(range_all)
                //range_all.compareEndPoints()比較兩個端點，如果range_all比range更往左(further to the left)，則                //返回小於0的值，則range_all往右移一點，直到兩個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
                // 計算一下\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 action="a.cgi">
<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)"
                            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>

本文章原先以中文撰寫並發佈於 aliyun.com，亦設英文版本，僅作資訊用途。本網站不對文章的準確性，完整性或可靠性或其任何翻譯作出任何明示或暗示的陳述或保證。如對該文章有任何疑慮或投訴，請傳送電郵至 info-contact@alibabacloud.com 並提供相關疑慮或投訴的詳細說明。職員會於 5 個工作天內與您聯絡，一經驗證之後，即會刪除該侵權內容。

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