获取/设置光标位置,兼容Input TextArea

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<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<title>JavaScript 获取/设置光标位置,兼容Input&&TextArea。</title> 
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> 
<style> 
body { margin: 32px; font-family: Verdana, sans-serif; font-size: 13px; } 
.title { font-size: 18px; font-weight: bolder;margin:40px 0; } 
.input { width: 50%; font-family: Verdana, sans-serif; font-size: 13px; text-indent: 2px; } 
</style> 
<script> 
//获取光标位置 
//单行文本框 
function getPositionForInput(ctrl){ 
var CaretPos = 0; 
if (document.selection) { // IE Support 
ctrl.focus(); 
var Sel = document.selection.createRange(); 
Sel.moveStart('character', -ctrl.value.length); 
CaretPos = Sel.text.length; 
}else if(ctrl.selectionStart || ctrl.selectionStart == '0'){// Firefox support 
CaretPos = ctrl.selectionStart; 
} 
return (CaretPos); 
} 
//多行文本框 
function getPositionForTextArea(ctrl) { 
var CaretPos = 0; 
if(document.selection) {// IE Support 
ctrl.focus(); 
var Sel = document.selection.createRange(); 
var Sel2 = Sel.duplicate(); 
Sel2.moveToElementText(ctrl); 
var CaretPos = -1; 
while(Sel2.inRange(Sel)){ 
Sel2.moveStart('character'); 
CaretPos++; 
} 
}else if(ctrl.selectionStart || ctrl.selectionStart == '0'){// Firefox support 
CaretPos = ctrl.selectionStart; 
} 
return (CaretPos); 
} 
//设置光标位置函数 
function setCursorPosition(ctrl, pos){ 
if(ctrl.setSelectionRange){ 
ctrl.focus(); 
ctrl.setSelectionRange(pos,pos); 
} 
else if (ctrl.createTextRange) { 
var range = ctrl.createTextRange(); 
range.collapse(true); 
range.moveEnd('character', pos); 
range.moveStart('character', pos); 
range.select(); 
} 
} 
//test 
function process( id,targetId ){ 
var no = document.getElementById(id).value; 
setCursorPosition(document.getElementById(targetId),no); 
} 
</script> 
</head> 
<body> 
<div class="title">JavaScript 获取/设置光标位置,兼容Input&&TextArea：</div> 
<div class="title">单行文本框</div> 
<p><input class="input" id="textbox" name="textbox" value="Hi,www.jb51.net!!!" /></p> 

<input type="button" onclick="alert( getPositionForInput( document.getElementById('textbox') ) )" value="Get Position"> 
输入位置: <input type="text" id="no1" size="1" /><input type="button" onclick="process('no1','textbox');" value="Set Position"> 

<div class="title">多行文本框</div> 
<textarea id="zhangdanNum" name="zhangdanNum" style="height:66px;246px;overflow:hidden">Hi,CssRain!!!</textarea> 
<input type="button" onclick="alert( getPositionForTextArea( document.getElementById('zhangdanNum') ) )" value="Get Position"> 
输入位置: <input type="text" id="no2" size="1" /><input type="button" onclick="process('no2','zhangdanNum');" value="Set Position"> 
</body> 
</html>
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