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YUI Library Examples: Menu Family: Adding A Context Menu To A Table

Menu Family: Adding A Context Menu To A Table

This example creates context menu for an HTML table and illustrates how the content of a ContextMenu instance can be replaced on the fly based on the element that triggered its display.

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When adding context menus to large data structures like a <table> or large list (<ol> or <ul>), it is recommended to bind a single YAHOO.widget.ContextMenu instance to the structure's root element, than to each of its child nodes (<tr>s or <li>s). Doing so significantly improves the performance of a web page or application by reducing the number of "contextmenu" event handlers as well as the number of YAHOO.widget.ContextMenu instances in memory.

Begin by creating an <table> and giving <tr> elements that should have the same context menu a similar class name.

Next, use the onContentReady method of the Event utility to listen for when the <table> element is are ready to be scripted.

1YAHOO.util.Event.onContentReady("dataset", function () { 
2 
3 
4});          
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Inside the function passed to the Event Utility's onContentReady method, create a shortcut to the Dom Utility (since it will be used frequently) and an object literal that maps each class name to a set of MenuItem configuration properties.

1YAHOO.util.Event.onContentReady("dataset", function () { 
2 
3    var Dom = YAHOO.util.Dom; 
4 
5    /*
6        Map of CSS class names to arrays of MenuItem 
7        configuration properties.
8    */ 
9 
10    var oContextMenuItems = { 
11     
12        "type1": [ 
13                    "Context Menu 1, Item 1",  
14                    { 
15                        text: "Context Menu 1, Item 2",  
16                        submenu: {  
17                                    id: "submenu1",  
18                                    lazyload: true,  
19                                    itemdata: [ 
20                                        "Context Menu 1 Submenu, Item 1",  
21                                        "Context Menu 1 Submenu, Item 2",  
22                                        "Context Menu 1 Submenu, Item 3",  
23                                        "Context Menu 1 Submenu, Item 4" 
24                                    ]  
25                                }  
26                    },  
27                    "Context Menu 1, Item 3",  
28                    "Context Menu 1, Item 4" 
29                ], 
30 
31        "type2": [ 
32                    "Context Menu 2, Item 1",  
33                    "Context Menu 2, Item 2",  
34                    "Context Menu 2, Item 3",  
35                    "Context Menu 2, Item 4",  
36                    "Context Menu 2, Item 5",  
37                    "Context Menu 2, Item 6",  
38                    "Context Menu 2, Item 7",  
39                    "Context Menu 2, Item 8",  
40                    "Context Menu 2, Item 9",  
41                    "Context Menu 2, Item 10" 
42                ], 
43 
44        "type3": [ 
45                    "Context Menu 3, Item 1",  
46                    "Context Menu 3, Item 2",  
47                    "Context Menu 3, Item 3",  
48                    "Context Menu 3, Item 4" 
49                ], 
50 
51        "type4": [ 
52                    "Context Menu 4, Item 1",  
53                    "Context Menu 4, Item 2" 
54                ], 
55 
56        "type5": [ 
57                    "Context Menu 5, Item 1",  
58                    "Context Menu 5, Item 2",  
59                    "Context Menu 5, Item 3",  
60                    "Context Menu 5, Item 4",  
61                    "Context Menu 5, Item 5",  
62                    "Context Menu 5, Item 6" 
63                ] 
64     
65    }; 
66 
67}); 
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Lastly, add a "beforeShow" event handler to the ContextMenu instance. This event handler makes use of the "contextEventTarget" property to determine which <tr> element was the target of the "contextmenu" event. Once found, the <tr> element's class name is used to look up its corresponding menu items in the "oContextMenuItems" map, which are then added to the ContextMenu instance via the "addItems" method.

1YAHOO.util.Event.onContentReady("dataset", function () { 
2 
3    var Dom = YAHOO.util.Dom; 
4 
5    /*
6        Map of CSS class names to arrays of MenuItem 
7        configuration properties.
8    */ 
9 
10    var oContextMenuItems = { 
11     
12        "type1": [ 
13                    "Context Menu 1, Item 1",  
14                    { 
15                        text: "Context Menu 1, Item 2",  
16                        submenu: {  
17                                    id: "submenu1",  
18                                    lazyload: true,  
19                                    itemdata: [ 
20                                        "Context Menu 1 Submenu, Item 1",  
21                                        "Context Menu 1 Submenu, Item 2",  
22                                        "Context Menu 1 Submenu, Item 3",  
23                                        "Context Menu 1 Submenu, Item 4" 
24                                    ]  
25                                }  
26                    },  
27                    "Context Menu 1, Item 3",  
28                    "Context Menu 1, Item 4" 
29                ], 
30 
31        "type2": [ 
32                    "Context Menu 2, Item 1",  
33                    "Context Menu 2, Item 2",  
34                    "Context Menu 2, Item 3",  
35                    "Context Menu 2, Item 4",  
36                    "Context Menu 2, Item 5",  
37                    "Context Menu 2, Item 6",  
38                    "Context Menu 2, Item 7",  
39                    "Context Menu 2, Item 8",  
40                    "Context Menu 2, Item 9",  
41                    "Context Menu 2, Item 10" 
42                ], 
43 
44        "type3": [ 
45                    "Context Menu 3, Item 1",  
46                    "Context Menu 3, Item 2",  
47                    "Context Menu 3, Item 3",  
48                    "Context Menu 3, Item 4" 
49                ], 
50 
51        "type4": [ 
52                    "Context Menu 4, Item 1",  
53                    "Context Menu 4, Item 2" 
54                ], 
55 
56        "type5": [ 
57                    "Context Menu 5, Item 1",  
58                    "Context Menu 5, Item 2",  
59                    "Context Menu 5, Item 3",  
60                    "Context Menu 5, Item 4",  
61                    "Context Menu 5, Item 5",  
62                    "Context Menu 5, Item 6" 
63                ] 
64     
65    }; 
66 
67 
68    var oSelectedTR;    // The currently selected TR 
69 
70 
71    /*
72         "beforeshow" event handler for the ContextMenu instance - 
73         replaces the content of the ContextMenu instance based 
74         on the CSS class name of the <tr> element that triggered
75         its display.
76    */ 
77 
78    function onContextMenuBeforeShow(p_sType, p_aArgs) { 
79 
80        var oTarget = this.contextEventTarget, 
81            aMenuItems, 
82            aClasses; 
83 
84 
85        if (this.getRoot() == this) { 
86 
87            /*
88                 Get the <tr> that was the target of the 
89                 "contextmenu" event.
90            */ 
91 
92            oSelectedTR = oTarget.nodeName.toUpperCase() == "TR" ?  
93                            oTarget : Dom.getAncestorByTagName(oTarget, "TR"); 
94 
95 
96            /*
97                Get the array of MenuItems for the CSS class name from 
98                the "oContextMenuItems" map.
99            */ 
100 
101            if (Dom.hasClass(oSelectedTR, "odd")) { 
102 
103                aClasses = oSelectedTR.className.split(" "); 
104 
105                aMenuItems = oContextMenuItems[aClasses[0]]; 
106             
107            } 
108            else { 
109                 
110                aMenuItems = oContextMenuItems[YAHOO.lang.trim(oSelectedTR.className)]; 
111 
112            } 
113 
114 
115            // Remove the existing content from the ContentMenu instance 
116 
117            this.clearContent(); 
118             
119 
120            // Add the new set of items to the ContentMenu instance                     
121             
122            this.addItems(aMenuItems); 
123 
124 
125            // Render the ContextMenu instance with the new content 
126 
127            this.render(); 
128 
129 
130            /*
131                 Highlight the <tr> element in the table that was 
132                 the target of the "contextmenu" event.
133            */ 
134 
135            Dom.addClass(oSelectedTR, "selected"); 
136         
137        } 
138         
139    } 
140 
141 
142    /*
143         "hide" event handler for the ContextMenu - used to 
144         clear the selected <tr> element in the table.
145    */ 
146 
147    function onContextMenuHide(p_sType, p_aArgs) { 
148 
149        if (this.getRoot() == this && oSelectedTR) { 
150 
151            Dom.removeClass(oSelectedTR, "selected"); 
152         
153        } 
154     
155    } 
156 
157 
158    /*
159         Instantiate a ContextMenu:  The first argument passed to 
160         the constructor is the id of the element to be created; the 
161         second is an object literal of configuration properties.
162    */ 
163 
164    var oContextMenu = new YAHOO.widget.ContextMenu("contextmenu", {  
165                                                            trigger: "dataset",  
166                                                            lazyload: true  
167                                                            }); 
168 
169     
170    /*
171         Subscribe to the ContextMenu instance's "beforeshow" and 
172         "hide" events.
173    */ 
174 
175    oContextMenu.subscribe("beforeShow", onContextMenuBeforeShow); 
176    oContextMenu.subscribe("hide", onContextMenuHide);             
177 
178}); 
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Configuration for This Example

You can load the necessary JavaScript and CSS for this example from Yahoo's servers. Click here to load the YUI Dependency Configurator with all of this example's dependencies preconfigured.

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