看Discuz!附件上传时候的选择框做的很不错
就拿jQuery练手顺手写了一个
jQuery多附件上传的演示效果就如Discuz!的上传选择框是一样的，不同的只是代码，现在拿出来给大家分享一下。：）

代码如下：

var aid = 1;
var attachexts = new Array();
var attachwh = new Array();

function addAttach() {
    newnode = $("#attachbodyhidden > tr").clone();
    var id = aid;
    var tags;
    tags = newnode.find("input");
    for(i in tags) {
        if(tags[i].name == 'attach[]') {
            tags[i].id = 'attach_' + id;
            tags[i].onchange = function() {insertAttach(id)};
            tags[i].unselectable = 'on';
        }
        if(tags[i].name == 'localid[]') {
            tags[i].value = id;
        }
    }
    tags = newnode.find("span");
    for(i in tags) {
        if(tags[i].id == 'localfile[]') {
            tags[i].id = 'localfile_' + id;
        }
    }
    aid++;
    $("#attachbody").append(newnode);
}

function insertAttach(id) {
    var localimgpreview = '';
    var path = $("#attach_" + id).attr("value");
    var ext = path.lastIndexOf('.') == -1 ? '' : path.substr(path.lastIndexOf('.') + 1, path.length).toLowerCase();
    var re = new RegExp("(^|\\s|,)" + ext + "($|\\s|,)", "ig");
    var localfile = $("#attach_" + id).attr("value").substr($("#attach_" + id).attr("value").replace(/\\/g, '/').lastIndexOf('/') + 1);
    attachexts[id] = in_array(ext, ['gif', 'jpg', 'png', 'bmp']) ? 2 : 1;

    $("#localfile_" + id).html('<a href="###delAttach" onclick="delAttach(' + id + ')">[' + lang['post_attachment_deletelink'] + ']</a> <a href="###insertAttach" title="' + lang['post_attachment_insert'] + '" onclick="insertAttachtext(' + id + ', ' + attachexts[id] + ');return false;">[' + lang['post_attachment_insertlink'] + ']</a> <span id="localimgpreview_' + id + '" > </span><span class="smalltxt">[' +id + ']</span> ' + localfile + '');
    $("#attach_" + id).css("display",'none');//style.display = 'none';
    addAttach();
}

function delAttach(id) {
    $("#attach_" + id).parent().parent().remove();
    $("#attachbody").html() == '' && addAttach();
}

$(document).ready(function() {
    addAttach();
});