jQuery file upload cropper的 click .preview事件没有绑定成功

测试

修改https://github.com/tkvw/jQuery-File-Upload/blob/master/basic-plus.html

var node = $('<p id="chuck" class="preview"/>')
    .append($('<span/>').text(file.name));

给p增加id和class，在页面加载后，

打开浏览器的console，然后手动执行，然后单击图片。会发现这个事件是会触发的

$(".preview").on("click", function(){
alert("test");
})

但是jquery.fileupload-image-editor.js中的没有触发，事件应该是绑定了

手动移除事件

$(".preview").off("click");  https://stackoverflow.com/questions/209029/best-way-to-remove-an-event-handler-in-jquery

分析

1.jquery.fileupload-image-editor.js定义了uploadImageEditorPreviewSelector

uploadImageEditorPreviewSelector: 'click .preview',

2,.jquery.fileupload-ui.js中定义了filesContainer
// The container for the list of files. If undefined, it is set to
// an element with class "files" inside of the widget element:
filesContainer: undefined,

_initEventHandlers: function () {
this._super();

var handlers = {};
handlers[this.options.uploadImageEditorPreviewSelector] = this._previewHandler.bind(this);

this._on(this.options.filesContainer, handlers);
},

文件上传之后

 jquery.fileupload.js中_onAdd: function (e, data) {

that._initResponseObject(newData);
that._initProgressObject(newData);
that._addConvenienceMethods(e, newData);
result = that._trigger(
'add',
$.Event('add', {delegatedEvent: e}),
newData
);
return result;

_initResponseObject: function (obj) {
var prop;
if (obj._response) {
for (prop in obj._response) {
if (obj._response.hasOwnProperty(prop)) {
delete obj._response[prop];
}
}
} else {
obj._response = {};
}
},

_initProgressObject: function (obj) {
var progress = {
loaded: 0,
total: 0,
bitrate: 0
};
if (obj._progress) {
$.extend(obj._progress, progress);
} else {
obj._progress = progress;
}
},

 // Adds convenience methods to the data callback argument:
        _addConvenienceMethods: function (e, data) {
            var that = this,
                getPromise = function (args) {
                    return $.Deferred().resolveWith(that, args).promise();
                };
            data.process = function (resolveFunc, rejectFunc) {
                if (resolveFunc || rejectFunc) {
                    data._processQueue = this._processQueue =
                        (this._processQueue || getPromise([this])).then(
                            function () {
                                if (data.errorThrown) {
                                    return $.Deferred()
                                        .rejectWith(that, [data]).promise();
                                }
                                return getPromise(arguments);
                            }
                        ).then(resolveFunc, rejectFunc);
                }
                return this._processQueue || getPromise([this]);
            };
            data.submit = function () {
                if (this.state() !== 'pending') {
                    data.jqXHR = this.jqXHR =
                        (that._trigger(
                            'submit',
                            $.Event('submit', {delegatedEvent: e}),
                            this
                        ) !== false) && that._onSend(e, this);
                }
                return this.jqXHR || that._getXHRPromise();
            };
            data.abort = function () {
                if (this.jqXHR) {
                    return this.jqXHR.abort();
                }
                this.errorThrown = 'abort';
                that._trigger('fail', null, this);
                return that._getXHRPromise(false);
            };
            data.state = function () {
                if (this.jqXHR) {
                    return that._getDeferredState(this.jqXHR);
                }
                if (this._processQueue) {
                    return that._getDeferredState(this._processQueue);
                }
            };
            data.processing = function () {
                return !this.jqXHR && this._processQueue && that
                    ._getDeferredState(this._processQueue) === 'pending';
            };
            data.progress = function () {
                return this._progress;
            };
            data.response = function () {
                return this._response;
            };
        },

jquery.ui.widget.js里面的_trigger函数

this.element.trigger( event, data );

打印event

jQuery.Event {originalEvent: j…y.Event, type: "fileuploadadd", isDefaultPrevented: ƒ, timeStamp: 1561917127348, jQuery111304105261403454039: true, …}currentTarget: input#fileuploaddata: undefineddelegateTarget: input#fileuploaddelegatedEvent: jQuery.Event {originalEvent: Event, type: "change", isDefaultPrevented: ƒ, timeStamp: 33359.854999987874, jQuery111304105261403454039: true, …}handleObj: {type: "fileuploadadd", origType: "fileuploadadd", data: undefined, handler: ƒ, guid: 20, …}isDefaultPrevented: ƒ returnFalse()isTrigger: 3jQuery111304105261403454039: truenamespace: ""namespace_re: nulloriginalEvent: jQuery.Event {type: "add", delegatedEvent: j…y.Event, timeStamp: 1561917127348, jQuery111304105261403454039: true}result: undefinedtarget: input#fileuploadtimeStamp: 1561917127348type: "fileuploadadd"__proto__: Object

 trigger后面的代码是

return !( $.isFunction( callback ) &&
callback.apply( this.element[0], [ event ].concat( data ) ) === false ||
event.isDefaultPrevented() );

callback对应下面的add

// The add callback is invoked as soon as files are added to the fileupload
            // widget (via file input selection, drag & drop or add API call).
            // See the basic file upload widget for more information:
            add: function (e, data) {
                if (e.isDefaultPrevented()) {
                    return false;
                }
                var $this = $(this),
                    that = $this.data('blueimp-fileupload') ||
                        $this.data('fileupload'),
                    options = that.options;
                data.context = that._renderUpload(data.files)
                    .data('data', data)
                    .addClass('processing');
                options.filesContainer[
                    options.prependFiles ? 'prepend' : 'append'
                ](data.context);
                that._forceReflow(data.context);
                that._transition(data.context);
                data.process(function () {        //这里的process是在_addConvenienceMethods里面定义的
                    return $this.fileupload('process', data);
                }).always(function () {
                    data.context.each(function (index) {
                        $(this).find('.size').text(
                            that._formatFileSize(data.files[index].size)
                        );
                    }).removeClass('processing');
                    that._renderPreviews(data);
                }).done(function () {
                    data.context.find('.start').prop('disabled', false);
                    if ((that._trigger('added', e, data) !== false) &&
                            (options.autoUpload || data.autoUpload) &&
                            data.autoUpload !== false) {
                        data.submit();
                    }
                }).fail(function () {
                    if (data.files.error) {
                        data.context.each(function (index) {
                            var error = data.files[index].error;
                            if (error) {
                                $(this).find('.error').text(error);
                            }
                        });
                    }
                });
            },

jquery.fileupload-ui.js里面的

 _renderUpload: function (files) {
            return this._renderTemplate(
                this.options.uploadTemplate,  //自己做测试的，这边是null
                files
            );
        },

_renderTemplate: function (func, files) {
            if (!func) {
                return $();   //自己做测试，这边就返回了
            }
            var result = func({
                files: files,
                formatFileSize: this._formatFileSize,
                options: this.options
            });
            if (result instanceof $) {
                return result;
            }
            return $(this.options.templatesContainer).html(result).children();
        },

_forceReflow: function (node) {
            return $.support.transition && node.length &&
                node[0].offsetWidth;
        },

_transition: function (node) {
            var dfd = $.Deferred();
            if ($.support.transition && node.hasClass('fade') && node.is(':visible')) {
                node.bind(
                    $.support.transition.end,
                    function (e) {
                        // Make sure we don't respond to other transitions events
                        // in the container element, e.g. from button elements:
                        if (e.target === node[0]) {
                            node.unbind($.support.transition.end);
                            dfd.resolveWith(node);
                        }
                    }
                ).toggleClass('in');
            } else {
                node.toggleClass('in');
                dfd.resolveWith(node);
            }
            return dfd;
        },

 data.process = function (resolveFunc, rejectFunc) {
                if (resolveFunc || rejectFunc) {
                    data._processQueue = this._processQueue =
                        (this._processQueue || getPromise([this])).then(
                            function () {
                                if (data.errorThrown) {
                                    return $.Deferred()
                                        .rejectWith(that, [data]).promise();
                                }
                                return getPromise(arguments);
                            }
                        ).then(resolveFunc, rejectFunc);
                }
                return this._processQueue || getPromise([this]);
            };

然后跳转jquery.fileupload-ui.js里面

 // Processes the files given as files property of the data parameter,
        // returns a Promise object that allows to bind callbacks:
        process: function (data) {
            var that = this,
                options = $.extend({}, this.options, data);
            if (options.processQueue && options.processQueue.length) {
                this._transformProcessQueue(options);
                if (this._processing === 0) {
                    this._trigger('processstart');
                }
                $.each(data.files, function (index) {
                    var opts = index ? $.extend({}, options) : options,
                        func = function () {
                            if (data.errorThrown) {
                                return $.Deferred()
                                        .rejectWith(that, [data]).promise();
                            }
                            return that._processFile(opts, data);
                        };
                    opts.index = index;
                    that._processing += 1;
                    that._processingQueue = that._processingQueue.then(func, func)
                        .always(function () {
                            that._processing -= 1;
                            if (that._processing === 0) {
                                that._trigger('processstop');
                            }
                        });
                });
            }
            return this._processingQueue;
        },

// Replaces the settings of each processQueue item that
        // are strings starting with an "@", using the remaining
        // substring as key for the option map,
        // e.g. "@autoUpload" is replaced with options.autoUpload:
        _transformProcessQueue: function (options) {
            var processQueue = [];
            $.each(options.processQueue, function () {
                var settings = {},
                    action = this.action,
                    prefix = this.prefix === true ? action : this.prefix;
                $.each(this, function (key, value) {
                    if ($.type(value) === 'string' &&
                            value.charAt(0) === '@') {
                        settings[key] = options[
                            value.slice(1) || (prefix ? prefix +
                                key.charAt(0).toUpperCase() + key.slice(1) : key)
                        ];
                    } else {
                        settings[key] = value;
                    }

                });
                processQueue.push(settings);
            });
            options.processQueue = processQueue;
        },

 processstart: function (e) {
                if (e.isDefaultPrevented()) {
                    return false;
                }
                $(this).addClass('fileupload-processing');
            },

然后是jquery.fileupload-process.js里面的

_processFile: function (data, originalData) {
            var that = this,
                dfd = $.Deferred().resolveWith(that, [data]),
                chain = dfd.promise();
            this._trigger('process', null, data);
            $.each(data.processQueue, function (i, settings) {
                var func = function (data) {
                    if (originalData.errorThrown) {
                        return $.Deferred()
                                .rejectWith(that, [originalData]).promise();
                    }
                    return that.processActions[settings.action].call(
                        that,
                        data,
                        settings
                    );
                };
                chain = chain.then(func, settings.always && func);
            });
            chain
                .done(function () {
                    that._trigger('processdone', null, data);
                    that._trigger('processalways', null, data);
                })
                .fail(function () {
                    that._trigger('processfail', null, data);
                    that._trigger('processalways', null, data);
                });
            return chain;
        },

 // Processes the files given as files property of the data parameter,
        // returns a Promise object that allows to bind callbacks:
        process: function (data) {
            var that = this,
                options = $.extend({}, this.options, data);
            if (options.processQueue && options.processQueue.length) {
                this._transformProcessQueue(options);
                if (this._processing === 0) {
                    this._trigger('processstart');
                }
                $.each(data.files, function (index) {
                    var opts = index ? $.extend({}, options) : options,
                        func = function () {
                            if (data.errorThrown) {
                                return $.Deferred()
                                        .rejectWith(that, [data]).promise();
                            }
                            return that._processFile(opts, data);
                        };
                    opts.index = index;
                    that._processing += 1;
                    that._processingQueue = that._processingQueue.then(func, func)
                        .always(function () {
                            that._processing -= 1;
                            if (that._processing === 0) {
                                that._trigger('processstop');
                            }
                        });
                });
            }
            return this._processingQueue;
        },

结论

绑定事件的时候依赖于this.options.filesContainer，这玩意不存在于jquery.fileupload.js里面

 _initEventHandlers: function () {
            this._super();

            var handlers = {};
            handlers[this.options.uploadImageEditorPreviewSelector] = this._previewHandler.bind(this);
            console.log(`filesContainer = ${this.options.filesContainer}`);
            this._on(this.options.filesContainer, handlers);
        },

而filesContainer在jquery.fileupload-ui.js中

 // The container for the list of files. If undefined, it is set to
            // an element with class "files" inside of the widget element:
            filesContainer: undefined,

_initFilesContainer: function () {
            var options = this.options;
            if (options.filesContainer === undefined) {
                options.filesContainer = this.element.find('.files');
            } else if (!(options.filesContainer instanceof $)) {
                options.filesContainer = $(options.filesContainer);
            }
        },

因为basic.html没有引用jquery.fileupload-ui.js，所以导致事件绑定失败。

 顺便打印一下this.element

console.log(`filesContainer = ${this.options.filesContainer}`);
console.log(this.element);

 自己手动复制函数，然后在_initEventHandlers里面调用

  _initFilesContainer: function () {
            var options = this.options;
            if (options.filesContainer === undefined) {
                options.filesContainer = this.element.find('.files');
            } else if (!(options.filesContainer instanceof $)) {
                options.filesContainer = $(options.filesContainer);
            }
        },
        _initEventHandlers: function () {
            this._super();
            this._initFilesContainer();
            var handlers = {};
            handlers[this.options.uploadImageEditorPreviewSelector] = this._previewHandler.bind(this);
            this._on(this.options.filesContainer, handlers);
        },

页面加载后，进行查询

$('#fileupload').fileupload('option', 'filesContainer')

在还有jquery.fileupload-ui.js里面还有关于uploadTemplateID的设置

options: {
    // By default, files added to the widget are uploaded as soon
    // as the user clicks on the start buttons. To enable automatic
    // uploads, set the following option to true:
    autoUpload: false,
    // The ID of the upload template:
    uploadTemplateId: 'template-upload',
    // The ID of the download template:
    downloadTemplateId: 'template-download',