用JavaScript获取和设置textfield中光标位置
原文：http://www.webdeveloper.com/forum/showthread.php?t=74982
<html>
<body style="font-family: tahoma; font-size: 8pt;">
<script language="JavaScript">
/*
** Returns the caret (cursor) position of the specified text field.
** Return value range is 0-oField.length.
*/
function doGetCaretPosition (oField) {
// Initialize
var iCaretPos = 0;
// IE Support
if (document.selection) {
// Set focus on the element
oField.focus ();
// To get cursor position, get empty selection range
var oSel = document.selection.createRange ();
// Move selection start to 0 position
oSel.moveStart ('character', -oField.value.length);
// The caret position is selection length
iCaretPos = oSel.text.length;
}
// Firefox support
else if (oField.selectionStart || oField.selectionStart == '0')
iCaretPos = oField.selectionStart;
// Return results
return (iCaretPos);
}
/*
** Sets the caret (cursor) position of the specified text field.
** Valid positions are 0-oField.length.
*/
function doSetCaretPosition (oField, iCaretPos) {
// IE Support
if (document.selection) {
// Set focus on the element
oField.focus ();
// Create empty selection range
var oSel = document.selection.createRange ();
// Move selection start and end to 0 position
oSel.moveStart ('character', -oField.value.length);
// Move selection start and end to desired position
oSel.moveStart ('character', iCaretPos);
oSel.moveEnd ('character', 0);
oSel.select ();
}
// Firefox support
else if (oField.selectionStart || oField.selectionStart == '0') {
oField.selectionStart = iCaretPos;
oField.selectionEnd = iCaretPos;
oField.focus ();
}
}
</script>
<form name="blah">
Text Field: <input type="text" name="nameEdit" value="">
<input type="button" value="Get Caret" onClick="document.getElementById('where').value=doGetCaretPosition (document.forms[0].elements[0]);">
<input id="where">
<hr size=1 noshade>
New Position: <input type="text" name="newPosValue" value="">
<input type="button" value="Set Caret" onClick="doSetCaretPosition (document.blah.nameEdit, parseInt (document.blah.newPosValue.value));">
</form>
</body>
</html>
<body style="font-family: tahoma; font-size: 8pt;">
<script language="JavaScript">
/*
** Returns the caret (cursor) position of the specified text field.
** Return value range is 0-oField.length.
*/
function doGetCaretPosition (oField) {
// Initialize
var iCaretPos = 0;
// IE Support
if (document.selection) {
// Set focus on the element
oField.focus ();
// To get cursor position, get empty selection range
var oSel = document.selection.createRange ();
// Move selection start to 0 position
oSel.moveStart ('character', -oField.value.length);
// The caret position is selection length
iCaretPos = oSel.text.length;
}
// Firefox support
else if (oField.selectionStart || oField.selectionStart == '0')
iCaretPos = oField.selectionStart;
// Return results
return (iCaretPos);
}
/*
** Sets the caret (cursor) position of the specified text field.
** Valid positions are 0-oField.length.
*/
function doSetCaretPosition (oField, iCaretPos) {
// IE Support
if (document.selection) {
// Set focus on the element
oField.focus ();
// Create empty selection range
var oSel = document.selection.createRange ();
// Move selection start and end to 0 position
oSel.moveStart ('character', -oField.value.length);
// Move selection start and end to desired position
oSel.moveStart ('character', iCaretPos);
oSel.moveEnd ('character', 0);
oSel.select ();
}
// Firefox support
else if (oField.selectionStart || oField.selectionStart == '0') {
oField.selectionStart = iCaretPos;
oField.selectionEnd = iCaretPos;
oField.focus ();
}
}
</script>
<form name="blah">
Text Field: <input type="text" name="nameEdit" value="">
<input type="button" value="Get Caret" onClick="document.getElementById('where').value=doGetCaretPosition (document.forms[0].elements[0]);">
<input id="where">
<hr size=1 noshade>
New Position: <input type="text" name="newPosValue" value="">
<input type="button" value="Set Caret" onClick="doSetCaretPosition (document.blah.nameEdit, parseInt (document.blah.newPosValue.value));">
</form>
</body>
</html>