Added first stab at Javascript/Ajax helpers

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@888 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_view/helpers/javascript_helper.rb

+require File.dirname(__FILE__) + '/tag_helper'
+
+# You must call <%= define_javascript_functions %> in your application before using these helpers.
+module JavascriptTagHelper
+  def link_to_display_toggle(name, tags, html_options = {})
+    toggle_functions = [ tags ].flatten.collect { |tag| "toggle_display_by_id('#{tag}'); " }.join
+    content_tag(
+      "a", name, 
+      html_options.symbolize_keys.merge(:href => "#", :onclick => "#{toggle_functions}; #{html_options['onclick']}; return false;")
+    )
+  end
+  
+  def link_to_function(name, function, html_options = {})
+    content_tag(
+      "a", name, 
+      html_options.symbolize_keys.merge(:href => "#", :onclick => "#{function}; return false;")
+    )
+  end
+
+  def link_to_remote(name, options = {})  
+    link_to_function(name, remote_function(options))
+  end
+
+  def form_remote_tag(options = {})
+    options[:form] = true
+
+    options[:html] ||= { }
+    options[:html][:onsubmit] = "#{remote_function(options)}; return false;"
+
+    tag("form", options[:html], true)
+  end
+
+  def define_javascript_functions
+<<-EOF
+<script language="JavaScript">
+/* XMLHttpRequest Methods */
+
+function update_with_response() {
+  o(arguments[0]).innerHTML = xml_request(arguments[1], arguments[2]);
+}
+
+function xml_request() {
+  var url        = arguments[0];
+  var parameters = arguments[1];
+  var async      = arguments[2];
+  var type       = parameters ? "POST" : "GET";
+
+  req = xml_http_request_object();
+  req.open(type, url, async);
+  req.send(parameters);
+
+  return req.responseText;
+}
+
+function xml_http_request_object() {
+  var req = false;
+  try {
+    req = new ActiveXObject("Msxml2.XMLHTTP");
+  } catch (e) {
+    try {
+      req = new ActiveXObject("Microsoft.XMLHTTP");
+    } catch (E) {
+      req = false;
+    }
+  }
+
+  if (!req && typeof XMLHttpRequest!='undefined') {
+    req = new XMLHttpRequest();
+  }
+
+  return req;
+}
+
+
+/* Common methods ------------------------------ */
+
+function toggle_display_by_id(id) {
+  o(id).style.display = (o(id).style.display == "none") ? "" : "none";
+}
+
+function o(id) {
+  return document.getElementById(id);
+}
+
+
+/* Serialize a form by Sam Stephenson ------------------------------ */
+
+Form = {
+  Serializers: {
+    input: function(element) {
+      switch (element.type.toLowerCase()) {
+        case 'hidden':
+        case 'text':
+          return Form.Serializers.textarea(element);
+        case 'checkbox':  
+        case 'radio':
+          return Form.Serializers.inputSelector(element);
+      }
+    },
+    
+    inputSelector: function(element) {
+      if (element.checked)
+        return [element.name, element.value];
+    },
+    
+    textarea: function(element) {
+      return [element.name, element.value];
+    },
+    
+    select: function(element) {
+      var index = element.selectedIndex;
+      return [element.name, element.options[index].value];
+    }
+  },
+  
+  serialize: function(form) {
+    var elements = Form.getFormElements(form);
+    var queryComponents = new Array();
+    
+    for (var i = 0; i < elements.length; i++) {
+      var element = elements[i];
+      var method = element.tagName.toLowerCase();
+      
+      var parameter = Form.Serializers[method](element);
+      if (parameter) {
+        var queryComponent = encodeURIComponent(parameter[0]) + '=' +
+                             encodeURIComponent(parameter[1]);
+        queryComponents.push(queryComponent);
+      }
+    }
+    
+    return queryComponents.join('&');
+  },
+  
+  getFormElements: function(form) {
+    var elements = new Array();
+    for (tagName in Form.Serializers) {
+      var tagElements = form.getElementsByTagName(tagName);
+      for (var j = 0; j < tagElements.length; j++)
+        elements.push(tagElements[j]);
+    }
+    return elements;
+  }
+}
+</script>
+EOF
+  end
+
+  private
+    def remote_function(options)
+      function = options[:update] ? 
+        "update_with_response('#{options[:update]}', '#{url_for(options[:url])}'#{', Form.serialize(this)' if options[:form]})" :
+        "xml_request('#{url_for(options[:url])}'#{', Form.serialize(this)' if options[:form]})"
+
+      function = "#{options[:before]};#{function}" if options[:before]
+      function = "#{function};#{options[:after]}"  if options[:after]
+      
+      return function
+    end
+end
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