JScript Tree List Control v3.0

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Introduction

This is my third attempt at making a TreeListControl for Internet Explorer-based web applications. The first was very slow and required ASP to generate a tree. The second has lots of features, and even resizable columns, but, while it did not suffer from the freeze-up delays that occurred in the first one, was generally sluggish in operation if there were more than a few nodes on the screen. This latest version has tighter code and is generally more versatile all round. It doesn't have resizable columns, but it shouldn't be too hard to put them in. If I do that, I'll upload the updated version here. The only other major limitation of this control is that it is fixed-width. That is, you have to specify the exact width of each column, and this determines the control width.

Features that version 3.0 has are:

• Enable/disable column headings
• Enable/disable root node
• The ability to choose which column the tree appears in
• Dynamic loading of branches via XML files
• Completely dynamic updating of the tree structure after it has been generated, including:
  • remove nodes
  • add new nodes
  • remove nodes and re-add them somewhere else
  • insert before or after a specified node
  • expand/collapse branches
• optional row onclick action
• row highlights while being pointed at
• prevent specified columns from firing the row onclick event (e.g. for a column of checkboxes)

To use the control, simply include treelistcontrol.js and treelistcontrol.css in your html file, then, inside the element (body tag, div tag, or where ever) you want to render the tree inside, place a script tag and build the tree according to the API. A demo of how to do this is inside the included zip file.

Usage

See the API below for explanations of the tree's objects, and the file demo.htm for an example of how to use the tree.

1. Create a tree control
2. Create and add the columns to the tree
3. Add all the initial nodes to the tree
4. document.write the tree object to the page

Tree List Control v3.0 API

TreeListControl

TreeListControl(strRootNodeLabel, strRootNodeIconSrc, boolHideColumnHeadings, boolHideRootNode)

• strRootNodeLabel: the label to use for the root node
• strRootNodeIconSrc: the path to the node's icon
• boolHideColumnHeadings: don't show the column headings
• boolHideRootNode: don't show the root node

Properties

• showColumnHeadings: hide/show the column headings. The visibility of the column headings will automatically change depending on the state of this property.
• showRootNode: hide/show the root node. The visibility of the root node will automatically change depending on the state of this property.
• all: this is a collection (array) contain references to all the nodes that were assigned a non-null refKey when added to the tree. usage: mytree.all['mynoderefKey']
• allNodes: this is a collection containing references to every node in the tree, indexed by the node's automatically assigned ID property.
• rootNode: a reference to the tree's root node. This is of type TreeListControlNode.
• iconPath: the path to the location where the tree's images are stored. The default is 'tlcimages/'.

Methods

• addColumn( oColumnObject ): adds a column to the tree. Do not use this once the tree has been rendered to the page. Pass in a reference to a TreeListControlColumn object that defines the column's parameters.
• add( oNodeObject ): appends a node to the children of the root node. Pass in a reference to a previously created node.

TreeListControlColumn

TreeListControlColumn (intWidth, strTitle, boolPreventRowClickEvents)

• intWidth: the width, in pixels, of the column.
• strTitle: the heading/title of the column. Use a zero-length string if no title is desired.
• boolPreventRowClickEvents: when a row is clicked, it fires the onclick event for that row. Setting this parameter to true will prevent clicks in this row from firing that event.

TreeListControlNode

TreeListControlNode (boolShowChildren, strIconSrc, strXMLSrc, strReferenceKey)

• boolShowChildren: this specifies the initial expand/collapse state for the node.
• strIconSrc: the path to the icon image to use.
• strXMLSrc: if the children of this node are to be loaded at run-time when the node is expanded, this parameter should contain the URL of the XML file. Set to null or '' if not used.
• strReferenceKey: if you want to use your own identifiers for each node, instead of the automatically-assigned ID that each node has, specify the identifier here. It can be an integer or a string, and, once the node has been added to the tree, you can access the node via the all property of the TreeListControl object.

Properties

• onclick: the javascript to execute when the onclick event fires for that node. Only set this before the node has been added to the tree.

Methods

• expand: shows the node's children.
• collapse: hides the node's children.
• setText( strColumn1, strColumn2, ..., strColumnN ): sets the node's text in each column.
• setColumnText( intColumn, strText ): sets the text for the node in the specified column.
• add( oNodeObject ): appends a node object to this node's children. DO NOT use this method if this node has not yet been added to the tree.
• insertBefore( oNodeObject ): inserts the supplied node immediately before this node.
• insertAfter( oNodeObject ): inserts the supplied node directly after this node.
• remove(): removes this node from the tree completely and returns a reference to the node so that it can be reinserted elsewhere if desired.