获取光标在文本框的位置、设置光标至文本框末尾

// 获取光标在文本框的位置
function _getFocus(elem) {
    var index = 0;
    if (document.selection) {// IE Support
        elem.focus();
        var Sel = document.selection.createRange();
        if (elem.nodeName === 'TEXTAREA') {//textarea
            var Sel2 = Sel.duplicate();
            Sel2.moveToElementText(elem);
            var index = -1;
            while (Sel2.inRange(Sel)) {
                Sel2.moveStart('character');
                index++;
            };
        }
        else if (elem.nodeName === 'INPUT') {// input
            Sel.moveStart('character', -elem.value.length);
            index = Sel.text.length;
        }
    }
    else if (elem.selectionStart || elem.selectionStart == '0') { // Firefox support
        index = elem.selectionStart;
    }
    return (index);
}
//光标移动至末尾
function moveEnd(obj) {
    obj.focus();
    var len = obj.value.length;
    if (document.selection) {
        var sel = obj.createTextRange();
        sel.moveStart('character', len);
        sel.collapse();
        sel.select();
    } else if (typeof obj.selectionStart == 'number' && typeof obj.selectionEnd == 'number') {
        obj.selectionStart = obj.selectionEnd = len;
    }
}