JS Ajax实现文件上传

AjaxUpload.js

/**
 * AJAX Upload ( http://valums.com/ajax-upload/ ) 
 * Copyright (c) Andris Valums
 * Licensed under the MIT license ( http://valums.com/mit-license/ )
 * Thanks to Gary Haran, David Mark, Corey Burns and others for contributions 
 */
(function () {
    /* global window */
    /* jslint browser: true, devel: true, undef: true, nomen: true, bitwise: true, regexp: true, newcap: true, immed: true */

    /**
     * Wrapper for FireBug's console.log
     */

    function log() {
        if (typeof (console) != 'undefined' && typeof (console.log) == 'function') {
            Array.prototype.unshift.call(arguments, '[Ajax Upload]');
            console.log(Array.prototype.join.call(arguments, ' '));
        }
    }

    /**
     * Attaches event to a dom element.
     * @param {Element} el
     * @param type event name
     * @param fn callback This refers to the passed element
     */

    function addEvent(el, type, fn) {
        if (el.addEventListener) {
            el.addEventListener(type, fn, false);
        } else if (el.attachEvent) {
            el.attachEvent('on' + type, function () {
                fn.call(el);
            });
        } else {
            throw new Error('not supported or DOM not loaded');
        }
    }

    /**
     * Attaches resize event to a window, limiting
     * number of event fired. Fires only when encounteres
     * delay of 100 after series of events.
     * 
     * Some browsers fire event multiple times when resizing
     * http://www.quirksmode.org/dom/events/resize.html
     * 
     * @param fn callback This refers to the passed element
     */

    function addResizeEvent(fn) {
        var timeout;

        addEvent(window, 'resize', function () {
            if (timeout) {
                clearTimeout(timeout);
            }
            timeout = setTimeout(fn, 100);
        });
    }

    // Needs more testing, will be rewriten for next version        
    // getOffset function copied from jQuery lib (http://jquery.com/)
    if (document.documentElement.getBoundingClientRect) {
        // Get Offset using getBoundingClientRect
        // http://ejohn.org/blog/getboundingclientrect-is-awesome/
        var getOffset = function (el) {
            var box = el.getBoundingClientRect();
            var doc = el.ownerDocument;
            var body = doc.body;
            var docElem = doc.documentElement; // for ie 
            var clientTop = docElem.clientTop || body.clientTop || 0;
            var clientLeft = docElem.clientLeft || body.clientLeft || 0;

            // In Internet Explorer 7 getBoundingClientRect property is treated as physical,
            // while others are logical. Make all logical, like in IE8.	
            var zoom = 1;
            if (body.getBoundingClientRect) {
                var bound = body.getBoundingClientRect();
                zoom = (bound.right - bound.left) / body.clientWidth;
            }

            if (zoom > 1) {
                clientTop = 0;
                clientLeft = 0;
            }

            var top = box.top / zoom + (window.pageYOffset || docElem && docElem.scrollTop / zoom || body.scrollTop / zoom) - clientTop,
                left = box.left / zoom + (window.pageXOffset || docElem && docElem.scrollLeft / zoom || body.scrollLeft / zoom) - clientLeft;

            return {
                top: top,
                left: left
            };
        };
    } else {
        // Get offset adding all offsets 
        var getOffset = function (el) {
            var top = 0,
                left = 0;
            do {
                top += el.offsetTop || 0;
                left += el.offsetLeft || 0;
                el = el.offsetParent;
            } while (el);

            return {
                left: left,
                top: top
            };
        };
    }

    /**
     * Returns left, top, right and bottom properties describing the border-box,
     * in pixels, with the top-left relative to the body
     * @param {Element} el
     * @return {Object} Contains left, top, right,bottom
     */

    function getBox(el) {
        var left, right, top, bottom;
        var offset = getOffset(el);
        left = offset.left;
        top = offset.top;

        right = left + el.offsetWidth;
        bottom = top + el.offsetHeight;

        return {
            left: left,
            right: right,
            top: top,
            bottom: bottom
        };
    }

    /**
     * Helper that takes object literal
     * and add all properties to element.style
     * @param {Element} el
     * @param {Object} styles
     */

    function addStyles(el, styles) {
        for (var name in styles) {
            if (styles.hasOwnProperty(name)) {
                el.style[name] = styles[name];
            }
        }
    }

    /**
     * Function places an absolutely positioned
     * element on top of the specified element
     * copying position and dimentions.
     * @param {Element} from
     * @param {Element} to
     */

    function copyLayout(from, to) {
        var box = getBox(from);

        addStyles(to, {
            position: 'absolute',
            left: box.left + 'px',
            top: box.top + 'px',
            width: from.offsetWidth + 'px',
            height: from.offsetHeight + 'px'
        });
    }

    /**
     * Creates and returns element from html chunk
     * Uses innerHTML to create an element
     */
    var toElement = (function () {
        var div = document.createElement('div');
        return function (html) {
            div.innerHTML = html;
            var el = div.firstChild;
            return div.removeChild(el);
        };
    })();

    /**
     * Function generates unique id
     * @return unique id 
     */
    var getUID = (function () {
        var id = 0;
        return function () {
            return 'ValumsAjaxUpload' + id++;
        };
    })();

    /**
     * Get file name from path
     * @param {String} file path to file
     * @return filename
     */

    function fileFromPath(file) {
        return file.replace(/.*(\/|\\)/, "");
    }

    /**
     * Get file extension lowercase
     * @param {String} file name
     * @return file extenstion
     */

    function getExt(file) {
        return (-1 !== file.indexOf('.')) ? file.replace(/.*[.]/, '') : '';
    }

    function hasClass(el, name) {
        var re = new RegExp('\\b' + name + '\\b');
        return re.test(el.className);
    }

    function addClass(el, name) {
        if (!hasClass(el, name)) {
            el.className += ' ' + name;
        }
    }

    function removeClass(el, name) {
        var re = new RegExp('\\b' + name + '\\b');
        el.className = el.className.replace(re, '');
    }

    function removeNode(el) {
        el.parentNode.removeChild(el);
    }

    /**
     * Easy styling and uploading
     * @constructor
     * @param button An element you want convert to 
     * upload button. Tested dimentions up to 500x500px
     * @param {Object} options See defaults below.
     */
    window.AjaxUpload = function (button, options) {
        this._settings = {
            // Location of the server-side upload script
            action: 'upload.php',
            // File upload name
            name: 'userfile',
            // Additional data to send
            data: {},
            // Submit file as soon as it's selected
            autoSubmit: true,
            // The type of data that you're expecting back from the server.
            // html and xml are detected automatically.
            // Only useful when you are using json data as a response.
            // Set to "json" in that case. 
            responseType: false,
            // Class applied to button when mouse is hovered
            hoverClass: 'hover',
            // Class applied to button when AU is disabled
            disabledClass: 'disabled',
            // When user selects a file, useful with autoSubmit disabled
            // You can return false to cancel upload			
            onChange: function (file, extension) { },
            // Callback to fire before file is uploaded
            // You can return false to cancel upload
            onSubmit: function (file, extension) { },
            // Fired when file upload is completed
            // WARNING! DO NOT USE "FALSE" STRING AS A RESPONSE!
            onComplete: function (file, response) { }
        };

        // Merge the users options with our defaults
        for (var i in options) {
            if (options.hasOwnProperty(i)) {
                this._settings[i] = options[i];
            }
        }

        // button isn't necessary a dom element
        if (button.jquery) {
            // jQuery object was passed
            button = button[0];
        } else if (typeof button == "string") {
            if (/^#.*/.test(button)) {
                // If jQuery user passes #elementId don't break it					
                button = button.slice(1);
            }

            button = document.getElementById(button);
        }

        if (!button || button.nodeType !== 1) {
            throw new Error("Please make sure that you're passing a valid element");
        }

        if (button.nodeName.toUpperCase() == 'A') {
            // disable link                       
            addEvent(button, 'click', function (e) {
                if (e && e.preventDefault) {
                    e.preventDefault();
                } else if (window.event) {
                    window.event.returnValue = false;
                }
            });
        }

        // DOM element
        this._button = button;
        // DOM element                 
        this._input = null;
        // If disabled clicking on button won't do anything
        this._disabled = false;

        // if the button was disabled before refresh if will remain
        // disabled in FireFox, let's fix it
        this.enable();

        this._rerouteClicks();
    };

    // assigning methods to our class
    AjaxUpload.prototype = {
        setData: function (data) {
            this._settings.data = data;
        },
        disable: function () {
            addClass(this._button, this._settings.disabledClass);
            this._disabled = true;

            var nodeName = this._button.nodeName.toUpperCase();
            if (nodeName == 'INPUT' || nodeName == 'BUTTON') {
                this._button.setAttribute('disabled', 'disabled');
            }

            // hide input
            if (this._input) {
                // We use visibility instead of display to fix problem with Safari 4
                // The problem is that the value of input doesn't change if it 
                // has display none when user selects a file           
                this._input.parentNode.style.visibility = 'hidden';
            }
        },
        enable: function () {
            removeClass(this._button, this._settings.disabledClass);
            this._button.removeAttribute('disabled');
            this._disabled = false;

        },
        /**
         * Creates invisible file input 
         * that will hover above the button
         * 

         */
        _createInput: function () {
            var self = this;

            var input = document.createElement("input");
            input.setAttribute('type', 'file');
            input.setAttribute('name', this._settings.name);

            addStyles(input, {
                'position': 'absolute',
                // in Opera only 'browse' button
                // is clickable and it is located at
                // the right side of the input
                'right': 0,
                'margin': 0,
                'padding': 0,
                'fontSize': '480px',
                'cursor': 'pointer'
            });

            var div = document.createElement("div");
            addStyles(div, {
                'display': 'block',
                'position': 'absolute',
                'overflow': 'hidden',
                'margin': 0,
                'padding': 0,
                'opacity': 0,
                // Make sure browse button is in the right side
                // in Internet Explorer
                'direction': 'ltr',
                //Max zIndex supported by Opera 9.0-9.2
                'zIndex': 2147483583
            });

            // Make sure that element opacity exists.
            // Otherwise use IE filter            
            if (div.style.opacity !== "0") {
                if (typeof (div.filters) == 'undefined') {
                    throw new Error('Opacity not supported by the browser');
                }
                div.style.filter = "alpha(opacity=0)";
            }

            addEvent(input, 'change', function () {

                if (!input || input.value === '') {
                    return;
                }

                // Get filename from input, required                
                // as some browsers have path instead of it          
                var file = fileFromPath(input.value);

                if (false === self._settings.onChange.call(self, file, getExt(file))) {
                    self._clearInput();
                    return;
                }

                // Submit form when value is changed
                if (self._settings.autoSubmit) {
                    self.submit();
                }
            });

            addEvent(input, 'mouseover', function () {
                addClass(self._button, self._settings.hoverClass);
            });

            addEvent(input, 'mouseout', function () {
                removeClass(self._button, self._settings.hoverClass);

                // We use visibility instead of display to fix problem with Safari 4
                // The problem is that the value of input doesn't change if it 
                // has display none when user selects a file           
                input.parentNode.style.visibility = 'hidden';

            });

            div.appendChild(input);
            document.body.appendChild(div);

            this._input = input;
        },
        _clearInput: function () {
            if (!this._input) {
                return;
            }

            // this._input.value = ''; Doesn't work in IE6                               
            removeNode(this._input.parentNode);
            this._input = null;
            this._createInput();

            removeClass(this._button, this._settings.hoverClass);
        },
        /**
         * Function makes sure that when user clicks upload button,
         * the this._input is clicked instead
         */
        _rerouteClicks: function () {
            var self = this;

            // IE will later display 'access denied' error
            // if you use using self._input.click()
            // other browsers just ignore click()

            addEvent(self._button, 'mouseover', function () {
                if (self._disabled) {
                    return;
                }

                if (!self._input) {
                    self._createInput();
                }

                var div = self._input.parentNode;
                copyLayout(self._button, div);
                div.style.visibility = 'visible';

            });


            // commented because we now hide input on mouseleave
            /**
             * When the window is resized the elements 
             * can be misaligned if button position depends
             * on window size
             */
            //addResizeEvent(function(){
            //    if (self._input){
            //        copyLayout(self._button, self._input.parentNode);
            //    }
            //});            

        },
        /**
         * Creates iframe with unique name
         * @return {Element} iframe
         */
        _createIframe: function () {
            // We can't use getTime, because it sometimes return
            // same value in safari :(
            var id = getUID();

            // We can't use following code as the name attribute
            // won't be properly registered in IE6, and new window
            // on form submit will open
            // var iframe = document.createElement('iframe');
            // iframe.setAttribute('name', id);                        

            var iframe = toElement('