将鼠标移到文本最后

//将鼠标移到文本最后
function set_focus(el) {
    el.focus();
    if (el instanceof jQuery) el = el[0];
    //el=el[0];  //jquery 对象转dom对象
    if ($.support.msie) {
        var range = document.selection.createRange();
        this.last = range;
        range.moveToElementText(el);
        range.select();
        document.selection.empty(); //取消选中
    }
    else {
        var range = document.createRange();
        range.selectNodeContents(el);
        range.collapse(false);
        var sel = window.getSelection();//适用于firefox和safari
        sel.removeAllRanges();//取消选中
        sel.addRange(range);
    }
}