问Jquery事件被多次调用

EN

var Upload =  {
    init: function ( config ) {
        this.config = config;
        this.bindEvents();
        this.counter = 1;
    },

    /**
     * Binds all events triggered by the user.
     */
    bindEvents: function () {
        this.config.photoContainer.children('li').children('input[name=images]').off();
        this.config.photoContainer.children('li').children('input[name=images]').on("change", this.photoAdded);
        this.config.photoContainer.children('li').children('p').children('a.removePhoto').on('click', this.removePhoto);
    },

    /**
     * Called when a new photo is selected in the input.
     */
    photoAdded: function ( evt ) {
        var self = Upload,
            file = this.files[0];
        $(this).hide();
        $(this).parent().append('<p class="photo" style="background-color: gray; color: white;">' + file.name + ' <a class="removePhoto" style="color: red;" href="#">X</a></p>');

        if(self.counter < 8) {  // Adds another button if needed.
            Upload.config.photoContainer.append( '<li><input type="file" name="images"></li>');
            self.counter++;
        } 
        Upload.bindEvents();
    },

    /**
     * Removes the <li> from the list.
     */
    removePhoto: function ( evt ) {
        var self = Upload;
        evt.preventDefault();

        $(this).off();
        $(this).parent().parent().remove();

        if(self.counter == 8) { // Adds a new input, if necessary.
            Upload.config.photoContainer.append( '<li><input type="file" name="images"></li>');
        }
        self.counter--;
        Upload.bindEvents();
    }
}

Upload.init({
    photoContainer: $('ul#photo-upload')
});