EDIT (Oct 2019):

6 years later and jQuery File Upload is clearly still driving folks insane. If you're finding little solace in the answers here, try a search of NPM for a modern alternative. It's not worth the hassle, I promise.

I recommended Uploadify in the previous edit but, as a commenter pointed out, they no longer appear to offer a free version. Uploadify was so 2013 anyway.

编辑:

Background

我正在try 使用Bluimp的jQuery File Upload来允许用户上传文件.Out of the box it works perfectly，按照设置说明进行操作.但要在我的网站上实际使用它，我希望能够做几件事:

• 在我现有的任何页面上包括上传程序
• Change the directory for uploaded files

插件的所有文件都位于根目录下的文件夹中.

I've tried...

• 将演示页面移到根目录并更新必要脚本的路径
• Changing the 'upload_dir' and 'upload_url' options in the UploadHandler.php file as suggested here.
• Changing the URL in the second line of the demo javascript

In all cases, the preview shows, and the progress bar runs, but the files fail to upload, and I get this error in the console: Uncaught TypeError: Cannot read property 'files' of undefined. I don't understand how all the parts of the plugin work which is making it difficult to debug.

Code

演示页面中的javascript:

$(function () {
'use strict';
// Change this to the location of your server-side upload handler:
var url = 'file_upload/server/php/UploadHandler.php',
    uploadButton = $('<button/>')
        .addClass('btn')
        .prop('disabled', true)
        .text('Processing...')
        .on('click', function () {
            var $this = $(this),
                data = $this.data();
            $this
                .off('click')
                .text('Abort')
                .on('click', function () {
                    $this.remove();
                    data.abort();
                });
            data.submit().always(function () {
                $this.remove();
            });
        });
$('#fileupload').fileupload({
    url: url,
    dataType: 'json',
    autoUpload: false,
    acceptFileTypes: /(\.|\/)(gif|jpe?g|png)$/i,
    maxFileSize: 5000000, // 5 MB
    // Enable image resizing, except for Android and Opera,
    // which actually support image resizing, but fail to
    // send Blob objects via XHR requests:
    disableImageResize: /Android(?!.*Chrome)|Opera/
        .test(window.navigator.userAgent),
    previewMaxWidth: 100,
    previewMaxHeight: 100,
    previewCrop: true
}).on('fileuploadadd', function (e, data) {
    data.context = $('<div/>').appendTo('#files');
    $.each(data.files, function (index, file) {
        var node = $('<p/>')
                .append($('<span/>').text(file.name));
        if (!index) {
            node
                .append('<br>')
                .append(uploadButton.clone(true).data(data));
        }
        node.appendTo(data.context);
    });
}).on('fileuploadprocessalways', function (e, data) {
    var index = data.index,
        file = data.files[index],
        node = $(data.context.children()[index]);
    if (file.preview) {
        node
            .prepend('<br>')
            .prepend(file.preview);
    }
    if (file.error) {
        node
            .append('<br>')
            .append(file.error);
    }
    if (index + 1 === data.files.length) {
        data.context.find('button')
            .text('Upload')
            .prop('disabled', !!data.files.error);
    }
}).on('fileuploadprogressall', function (e, data) {
    var progress = parseInt(data.loaded / data.total * 100, 10);
    $('#progress .bar').css(
        'width',
        progress + '%'
    );
}).on('fileuploaddone', function (e, data) {
    $.each(data.result.files, function (index, file) {
        var link = $('<a>')
            .attr('target', '_blank')
            .prop('href', file.url);
        $(data.context.children()[index])
            .wrap(link);
    });
}).on('fileuploadfail', function (e, data) {
    $.each(data.result.files, function (index, file) {
        var error = $('<span/>').text(file.error);
        $(data.context.children()[index])
            .append('<br>')
            .append(error);
    });
}).prop('disabled', !$.support.fileInput)
    .parent().addClass($.support.fileInput ? undefined : 'disabled');
});