prototype.js

《Ajax 实战》中文（有源码）详细简介了ajax

Insertion.Top.prototype = (new Abstract.Insertion('afterBegin')).extend({
  initializeRange: function() {
    this.range.selectNodeContents(this.element);
    this.range.collapse(true);
  },
  
  insertContent: function() {  
    this.element.insertBefore(this.fragment, this.element.firstChild);
  }
});

Insertion.Bottom = Class.create();
Insertion.Bottom.prototype = (new Abstract.Insertion('beforeEnd')).extend({
  initializeRange: function() {
    this.range.selectNodeContents(this.element);
    this.range.collapse(this.element);
  },
  
  insertContent: function() {
    this.element.appendChild(this.fragment);
  }
});

Insertion.After = Class.create();
Insertion.After.prototype = (new Abstract.Insertion('afterEnd')).extend({
  initializeRange: function() {
    this.range.setStartAfter(this.element);
  },
  
  insertContent: function() {
    this.element.parentNode.insertBefore(this.fragment, 
      this.element.nextSibling);
  }
});

var Field = {
  clear: function() {
    for (var i = 0; i < arguments.length; i++)
      $(arguments[i]).value = '';
  },

  focus: function(element) {
    $(element).focus();
  },
  
  present: function() {
    for (var i = 0; i < arguments.length; i++)
      if ($(arguments[i]).value == '') return false;
    return true;
  },
  
  select: function(element) {
    $(element).select();
  },
   
  activate: function(element) {
    $(element).focus();
    $(element).select();
  }
}

/*--------------------------------------------------------------------------*/

var Form = {
  serialize: function(form) {
    var elements = Form.getElements($(form));
    var queryComponents = new Array();
    
    for (var i = 0; i < elements.length; i++) {
      var queryComponent = Form.Element.serialize(elements[i]);
      if (queryComponent)
        queryComponents.push(queryComponent);
    }
    
    return queryComponents.join('&');
  },
  
  getElements: function(form) {
    var form = $(form);
    var elements = new Array();

    for (tagName in Form.Element.Serializers) {
      var tagElements = form.getElementsByTagName(tagName);
      for (var j = 0; j < tagElements.length; j++)
        elements.push(tagElements[j]);
    }
    return elements;
  },
  
  getInputs: function(form, typeName, name) {
    var form = $(form);
    var inputs = form.getElementsByTagName('input');
    
    if (!typeName && !name)
      return inputs;
      
    var matchingInputs = new Array();
    for (var i = 0; i < inputs.length; i++) {
      var input = inputs[i];
      if ((typeName && input.type != typeName) ||
          (name && input.name != name)) 
        continue;
      matchingInputs.push(input);
    }

    return matchingInputs;
  },

  disable: function(form) {
    var elements = Form.getElements(form);
    for (var i = 0; i < elements.length; i++) {
      var element = elements[i];
      element.blur();
      element.disabled = 'true';
    }
  },

  enable: function(form) {
    var elements = Form.getElements(form);
    for (var i = 0; i < elements.length; i++) {
      var element = elements[i];
      element.disabled = '';
    }
  },

  focusFirstElement: function(form) {
    var form = $(form);
    var elements = Form.getElements(form);
    for (var i = 0; i < elements.length; i++) {
      var element = elements[i];
      if (element.type != 'hidden' && !element.disabled) {
        Field.activate(element);
        break;
      }
    }
  },

  reset: function(form) {
    $(form).reset();
  }
}

Form.Element = {
  serialize: function(element) {
    var element = $(element);
    var method = element.tagName.toLowerCase();
    var parameter = Form.Element.Serializers[method](element);
    
    if (parameter)
      return encodeURIComponent(parameter[0]) + '=' + 
        encodeURIComponent(parameter[1]);                   
  },
  
  getValue: function(element) {
    var element = $(element);
    var method = element.tagName.toLowerCase();
    var parameter = Form.Element.Serializers[method](element);
    
    if (parameter) 
      return parameter[1];
  }
}

Form.Element.Serializers = {
  input: function(element) {
    switch (element.type.toLowerCase()) {
      case 'submit':
      case 'hidden':
      case 'password':
      case 'text':
        return Form.Element.Serializers.textarea(element);
      case 'checkbox':  
      case 'radio':
        return Form.Element.Serializers.inputSelector(element);
    }
    return false;
  },

  inputSelector: function(element) {
    if (element.checked)
      return [element.name, element.value];
  },

  textarea: function(element) {
    return [element.name, element.value];
  },

  select: function(element) {
    var value = '';
    if (element.type == 'select-one') {
      var index = element.selectedIndex;
      if (index >= 0)
        value = element.options[index].value || element.options[index].text;
    } else {
      value = new Array();
      for (var i = 0; i < element.length; i++) {
        var opt = element.options[i];
        if (opt.selected)
          value.push(opt.value || opt.text);
      }
    }
    return [element.name, value];
  }
}

/*--------------------------------------------------------------------------*/

var $F = Form.Element.getValue;

/*--------------------------------------------------------------------------*/

Abstract.TimedObserver = function() {}
Abstract.TimedObserver.prototype = {
  initialize: function(element, frequency, callback) {
    this.frequency = frequency;
    this.element   = $(element);
    this.callback  = callback;
    
    this.lastValue = this.getValue();
    this.registerCallback();
  },
  
  registerCallback: function() {
    setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
  },
  
  onTimerEvent: function() {
    var value = this.getValue();
    if (this.lastValue != value) {
      this.callback(this.element, value);
      this.lastValue = value;
    }
  }
}

Form.Element.Observer = Class.create();
Form.Element.Observer.prototype = (new Abstract.TimedObserver()).extend({
  getValue: function() {
    return Form.Element.getValue(this.element);
  }
});

Form.Observer = Class.create();
Form.Observer.prototype = (new Abstract.TimedObserver()).extend({
  getValue: function() {
    return Form.serialize(this.element);
  }
});

/*--------------------------------------------------------------------------*/

Abstract.EventObserver = function() {}
Abstract.EventObserver.prototype = {
  initialize: function(element, callback) {
    this.element  = $(element);
    this.callback = callback;
    
    this.lastValue = this.getValue();
    if (this.element.tagName.toLowerCase() == 'form')
      this.registerFormCallbacks();
    else
      this.registerCallback(this.element);
  },
  
  onElementEvent: function() {
    var value = this.getValue();
    if (this.lastValue != value) {
      this.callback(this.element, value);
      this.lastValue = value;
    }
  },
  
  registerFormCallbacks: function() {
    var elements = Form.getElements(this.element);
    for (var i = 0; i < elements.length; i++)
      this.registerCallback(elements[i]);
  },
  
  registerCallback: function(element) {
    if (element.type) {
      switch (element.type.toLowerCase()) {
        case 'checkbox':  
        case 'radio':
          element.target = this;
          element.prev_onclick = element.onclick || Prototype.emptyFunction;
          element.onclick = function() {
            this.prev_onclick(); 
            this.target.onElementEvent();
          }
          break;
        case 'password':
        case 'text':
        case 'textarea':
        case 'select-one':
        case 'select-multiple':
          element.target = this;
          element.prev_onchange = element.onchange || Prototype.emptyFunction;
          element.onchange = function() {
            this.prev_onchange(); 
            this.target.onElementEvent();
          }
          break;
      }
    }    
  }
}

Form.Element.EventObserver = Class.create();
Form.Element.EventObserver.prototype = (new Abstract.EventObserver()).extend({
  getValue: function() {
    return Form.Element.getValue(this.element);
  }
});

Form.EventObserver = Class.create();
Form.EventObserver.prototype = (new Abstract.EventObserver()).extend({
  getValue: function() {
    return Form.serialize(this.element);
  }
});


if (!window.Event) {
  var Event = new Object();
}

Object.extend(Event, {
  KEY_BACKSPACE: 8,
  KEY_TAB:       9,
  KEY_RETURN:   13,
  KEY_ESC:      27,
  KEY_LEFT:     37,
  KEY_UP:       38,
  KEY_RIGHT:    39,
  KEY_DOWN:     40,
  KEY_DELETE:   46,

  element: function(event) {
    return event.target || event.srcElement;
  },

  isLeftClick: function(event) {
    return (((event.which) && (event.which == 1)) ||
            ((event.button) && (event.button == 1)));
  },

  pointerX: function(event) {
    return event.pageX || (event.clientX + 
      (document.documentElement.scrollLeft || document.body.scrollLeft));
  },

  pointerY: function(event) {
    return event.pageY || (event.clientY + 
      (document.documentElement.scrollTop || document.body.scrollTop));
  },

  stop: function(event) {
    if (event.preventDefault) { 
      event.preventDefault(); 
      event.stopPropagation(); 
    } else {
      event.returnValue = false;
    }
  },

  // find the first node with the given tagName, starting from the
  // node the event was triggered on; traverses the DOM upwards
  findElement: function(event, tagName) {
    var element = Event.element(event);
    while (element.parentNode && (!element.tagName ||
        (element.tagName.toUpperCase() != tagName.toUpperCase())))
      element = element.parentNode;
    return element;
  },

  observers: false,
  
  _observeAndCache: function(element, name, observer, useCapture) {
    if (!this.observers) this.observers = [];
    if (element.addEventListener) {
      this.observers.push([element, name, observer, useCapture]);
      element.addEventListener(name, observer, useCapture);
    } else if (element.attachEvent) {
      this.observers.push([element, name, observer, useCapture]);
      element.attachEvent('on' + name, observer);
    }
  },
  
  unloadCache: function() {
    if (!Event.observers) return;
    for (var i = 0; i < Event.observers.length; i++) {
      Event.stopObserving.apply(this, Event.observers[i]);
      Event.observers[i][0] = null;
    }
    Event.observers = false;
  },

  observe: function(element, name, observer, useCapture) {
    var element = $(element);
    useCapture = useCapture || false;
    
    if (name == 'keypress' &&
        ((navigator.appVersion.indexOf('AppleWebKit') > 0) 
        || element.attachEvent))
      name = 'keydown';
    
    this._observeAndCache(element, name, observer, useCapture);
  },

  stopObserving: function(element, name, observer, useCapture) {
    var element = $(element);
    useCapture = useCapture || false;
    
    if (name == 'keypress' &&
        ((navigator.appVersion.indexOf('AppleWebKit') > 0) 
        || element.detachEvent))
      name = 'keydown';
    
    if (element.removeEventListener) {
      element.removeEventListener(name, observer, useCapture);
    } else if (element.detachEvent) {
      element.detachEvent('on' + name, observer);
    }
  }
});

/* prevent memory leaks in IE */
Event.observe(window, 'unload', Event.unloadCache, false);

var Position = {

  // set to true if needed, warning: firefox performance problems
  // NOT neeeded for page scrolling, only if draggable contained in
  // scrollable elements
  includeScrollOffsets: false, 

  // must be called before calling withinIncludingScrolloffset, every time the
  // page is scrolled
  prepare: function() {
    this.deltaX =  window.pageXOffset 
                || document.documentElement.scrollLeft 
                || document.body.scrollLeft 
                || 0;
    this.deltaY =  window.pageYOffset 
                || document.documentElement.scrollTop 
                || document.body.scrollTop 
                || 0;
  },

  realOffset: function(element) {
    var valueT = 0, valueL = 0;
    do {
      valueT += element.scrollTop  || 0;
      valueL += element.scrollLeft || 0; 
      element = element.parentNode;
    } while (element);
    return [valueL, valueT];
  },

  cumulativeOffset: function(element) {
    var valueT = 0, valueL = 0;
    do {
      valueT += element.offsetTop  || 0;
      valueL += element.offsetLeft || 0;
      element = element.offsetParent;
    } while (element);
    return [valueL, valueT];
  },

  // caches x/y coordinate pair to use with overlap
  within: function(element, x, y) {
    if (this.includeScrollOffsets)
      return this.withinIncludingScrolloffsets(element, x, y);
    this.xcomp = x;
    this.ycomp = y;
    this.offset = this.cumulativeOffset(element);

    return (y >= this.offset[1] &&
            y <  this.offset[1] + element.offsetHeight &&
            x >= this.offset[0] && 
            x <  this.offset[0] + element.offsetWidth);
  },

  withinIncludingScrolloffsets: function(element, x, y) {
    var offsetcache = this.realOffset(element);

    this.xcomp = x + offsetcache[0] - this.deltaX;
    this.ycomp = y + offsetcache[1] - this.deltaY;
    this.offset = this.cumulativeOffset(element);

    return (this.ycomp >= this.offset[1] &&
            this.ycomp <  this.offset[1] + element.offsetHeight &&
            this.xcomp >= this.offset[0] && 
            this.xcomp <  this.offset[0] + element.offsetWidth);
  },

  // within must be called directly before
  overlap: function(mode, element) {  
    if (!mode) return 0;  
    if (mode == 'vertical') 
      return ((this.offset[1] + element.offsetHeight) - this.ycomp) / 
        element.offsetHeight;
    if (mode == 'horizontal')
      return ((this.offset[0] + element.offsetWidth) - this.xcomp) / 
        element.offsetWidth;
  },

  clone: function(source, target) {
    source = $(source);
    target = $(target);
    target.style.position = 'absolute';
    var offsets = this.cumulativeOffset(source);
    target.style.top    = offsets[1] + 'px';
    target.style.left   = offsets[0] + 'px';
    target.style.width  = source.offsetWidth + 'px';
    target.style.height = source.offsetHeight + 'px';
  }
}