js获取和设置文本框光标的位置

function getCursortPosition(ctrl) {//获取光标位置函数
var CaretPos = 0; // IE Support
if (document.selection) {
ctrl.focus();
var Sel = document.selection.createRange();
Sel.moveStart('character', -ctrl.value.length);
CaretPos = Sel.text.length;
}
// Firefox support
else if (ctrl.selectionStart || ctrl.selectionStart == '0')
CaretPos = ctrl.selectionStart;
 return (CaretPos);
}

function setCaretPosition(ctrl, pos) {//设置光标位置函数
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();
}
}