cascadingutil.js

webwork source

/**********************************************************************/
/**********************************************************************/
/********                                                      ********/
/********              Cascading Select Util methods           ********/
/********             ===============================          ********/
/********         Author: Onyeje Bose ([e-mail])     ********/
/********                                                      ********/
/**********************************************************************/
/**********************************************************************/

	var pairs = new Map();			// caller and receiver pairs.

	/*	temp map to be reused by the dynamic selects created later. */
	
	var tmpMap;						
	var tmpDataMap;

	/****************************************************************
			Pairs Array Maniputlation 
	***************************************************************/
	
	function getKeyForPair( callerName, receiverName )
	{
		return ( callerName + "__" + receiverName );
	}
	
	function getDataMapForPair( callerName, receiverName )
	{
		return ( pairs.get( getKeyForPair( callerName, receiverName ) ) );
	}

	function setDataMapForPair( callerName, receiverName, map )
	{
		pairs.put( getKeyForPair( callerName, receiverName ), map );
	}
	
	function addCallerReceiverPair( callerName, receiverName )
	{
		pairs.put( getKeyForPair( callerName, receiverName ), new Map() );
	}

	/****************************************************************
			Receiver Select Maniputlation 
	***************************************************************/
		
	function getKeyFromCaller( callerName )
	{
		var caller = getElement( callerName );
		return ( caller.options[ caller.selectedIndex ].value );		
	}

	function callerHasChanged( callerName, receiverName )
	{
		var dataMap = getDataMapForPair( callerName, receiverName );
		var tmp = dataMap.get( getKeyFromCaller( callerName ) );
		if( tmp == null )	return;

		var tmpKeys = tmp.keySet();
		var tmpVals = tmp.valSet();

		clearList( receiverName );

		for( var index = 0; index < tmp.size(); index++ )
		{			
			addNewOptionToTarget( receiverName, tmpVals[ index ], tmpKeys[ index ] );
		}
	}

	function clearList( theListName )
	{
		var theList = getElement( theListName );
		var x = theList.length;
		while(  x >= 0 )
		{
			theList.options[ x-- ] = null;
		}	
	}
	
	function addNewOptionToTarget( targetName, txt, val )
	{
		var target = getElement( targetName );
		target.options[ target.options.length ] = new Option( txt, val, false, false );
	}

	function getElement( elmntName )
	{
		var numberForms = document.forms.length;
		for ( var formIndex = 0; formIndex < numberForms; formIndex++ )
		{
			var frm = document.forms[ formIndex ];
			var numberElms = frm.elements.length;
			for (var elmIndex = 0; elmIndex < numberElms; elmIndex++ )
			{
				if( elmntName == frm.elements[ elmIndex ].name )
				{
					return frm.elements[ elmIndex ];
				}
			}
		}		
		return null;
	}