New: Optimisation for sorting - when the sorting runs it will execute the sorting function a lot, particularly for large tables, so we want these functions to be as fast as possible. As it stood, each time the function ran it would prep the data and then do the required comparison - and it would do that data prep every time. This is pointless since toLowerCase (for example) is always going to give the same result when using the same input - so now introduced a third sorting function type (in addition to 'asc' and 'desc') called 'pre', which will pre-format the data to be sorted, only once for each item to be sorted, allowing the sorting comparison function itself to be really fast (simply just the comparison). This is also backwards compatible, if the sorting type doesn't have a 'pre'-formatting method then it will just use the two sorting functions as normal.

media/js/jquery.dataTables.js

@@ -581,21 +581,19 @@
 		/*
 		 * text sorting
 		 */
-		"string-asc": function ( a, b )
+		"string-pre": function ( a )
 		{
 			if ( typeof a != 'string' ) { a = ''; }
-			if ( typeof b != 'string' ) { b = ''; }
+			return a.toLowerCase();
-			var x = a.toLowerCase();
+		},
-			var y = b.toLowerCase();
+
+		"string-asc": function ( x, y )
+		{
 			return ((x < y) ? -1 : ((x > y) ? 1 : 0));
 		},
 		
-		"string-desc": function ( a, b )
+		"string-desc": function ( x, y )
 		{
-			if ( typeof a != 'string' ) { a = ''; }
-			if ( typeof b != 'string' ) { b = ''; }
-			var x = a.toLowerCase();
-			var y = b.toLowerCase();
 			return ((x < y) ? 1 : ((x > y) ? -1 : 0));
 		},
 		
@@ -603,17 +601,18 @@
 		/*
 		 * html sorting (ignore html tags)
 		 */
-		"html-asc": function ( a, b )
+		"html-pre": function ( a )
+		{
+			return a.replace( /<.*?>/g, "" ).toLowerCase();
+		},
+		
+		"html-asc": function ( x, y )
 		{
-			var x = a.replace( /<.*?>/g, "" ).toLowerCase();
-			var y = b.replace( /<.*?>/g, "" ).toLowerCase();
 			return ((x < y) ? -1 : ((x > y) ? 1 : 0));
 		},
 		
-		"html-desc": function ( a, b )
+		"html-desc": function ( x, y )
 		{
-			var x = a.replace( /<.*?>/g, "" ).toLowerCase();
-			var y = b.replace( /<.*?>/g, "" ).toLowerCase();
 			return ((x < y) ? 1 : ((x > y) ? -1 : 0));
 		},
 		
@@ -621,37 +620,24 @@
 		/*
 		 * date sorting
 		 */
-		"date-asc": function ( a, b )
+		"date-pre": function ( a )
 		{
 			var x = Date.parse( a );
-			var y = Date.parse( b );
 			
 			if ( isNaN(x) || x==="" )
 			{
-			x = Date.parse( "01/01/1970 00:00:00" );
+				x = Date.parse( "01/01/1970 00:00:00" );
 			}
-			if ( isNaN(y) || y==="" )
+			return x;
-			{
+		},
-				y =	Date.parse( "01/01/1970 00:00:00" );
+
-			}
+		"date-asc": function ( x, y )
-			
+		{
 			return x - y;
 		},
 		
-		"date-desc": function ( a, b )
+		"date-desc": function ( x, y )
 		{
-			var x = Date.parse( a );
-			var y = Date.parse( b );
-			
-			if ( isNaN(x) || x==="" )
-			{
-			x = Date.parse( "01/01/1970 00:00:00" );
-			}
-			if ( isNaN(y) || y==="" )
-			{
-				y =	Date.parse( "01/01/1970 00:00:00" );
-			}
-			
 			return y - x;
 		},
 		
@@ -659,17 +645,18 @@
 		/*
 		 * numerical sorting
 		 */
-		"numeric-asc": function ( a, b )
+		"numeric-asc": function ( a )
+		{
+			return (a=="-" || a==="") ? 0 : a*1;
+		},
+
+		"numeric-asc": function ( x, y )
 		{
-			var x = (a=="-" || a==="") ? 0 : a*1;
-			var y = (b=="-" || b==="") ? 0 : b*1;
 			return x - y;
 		},
 		
-		"numeric-desc": function ( a, b )
+		"numeric-desc": function ( x, y )
 		{
-			var x = (a=="-" || a==="") ? 0 : a*1;
-			var y = (b=="-" || b==="") ? 0 : b*1;
 			return y - x;
 		}
 	};
@@ -2688,6 +2675,7 @@
 				"nTr": null,
 				"_iId": oSettings.iNextId++,
 				"_aData": aDataIn,
+				"_aSortData": [],
 				"_anHidden": [],
 				"_sRowStripe": ""
 			};
@@ -2843,6 +2831,7 @@
 							"nTr": nTrs[i],
 							"_iId": oSettings.iNextId++,
 							"_aData": [],
+							"_aSortData": [],
 							"_anHidden": [],
 							"_sRowStripe": ''
 						} );
@@ -4649,7 +4638,7 @@
 		function _fnSort ( oSettings, bApplyClasses )
 		{
 			var
-				i, iLen, j, jLen,
+				i, iLen, j, jLen, k, kLen,
 				aaSort = [],
 			 	aiOrig = [],
 				oSort = _oExt.oSort,
@@ -4694,6 +4683,30 @@
 				{
 					aiOrig[ oSettings.aiDisplayMaster[i] ] = i;
 				}
+
+				/* Build an internal data array which is specific to the sort, so we can get and prep
+				 * the data to be sorted only once, rather than needing to do it every time the sorting
+				 * function runs. This make the sorting function a very simple comparison
+				 */
+				var iSortLen = aaSort.length;
+				var fnSortFormat;
+				for ( i=0, iLen=aoData.length ; i<iLen ; i++ )
+				{
+					for ( j=0 ; j<iSortLen ; j++ )
+					{
+						aDataSort = aoColumns[ aaSort[j][0] ].aDataSort;
+
+						for ( k=0, kLen=aDataSort.length ; k<kLen ; k++ )
+						{
+							sDataType = aoColumns[ aDataSort[k] ].sType;
+							fnSortFormat = oSort[ (sDataType ? sDataType : 'string')+"-pre" ];
+							
+							aoData[i]._aSortData[ aDataSort[k] ] = fnSortFormat ?
+								fnSortFormat( _fnGetCellData( oSettings, i, aDataSort[k], 'sort' ) ) :
+								_fnGetCellData( oSettings, i, aDataSort[k], 'sort' );
+						}
+					}
+				}
 				
 				/* Do the sort - here we want multi-column sorting based on a given data source (column)
 				 * and sorting function (from oSort) in a certain direction. It's reasonably complex to
@@ -4712,7 +4725,6 @@
 				 * test the next column. If all columns match, then we use a numeric sort on the row 
 				 * positions in the original data array to provide a stable sort.
 				 */
-				var iSortLen = aaSort.length;
 				oSettings.aiDisplayMaster.sort( function ( a, b ) {
 					var k, l, lLen, iTest, aDataSort, sDataType;
 					for ( k=0 ; k<iSortLen ; k++ )
@@ -4724,8 +4736,8 @@
 							sDataType = aoColumns[ aDataSort[l] ].sType;
 							
 							iTest = oSort[ (sDataType ? sDataType : 'string')+"-"+aaSort[k][1] ](
-								_fnGetCellData( oSettings, a, aDataSort[l], 'sort' ),
+								aoData[a]._aSortData[ aDataSort[l] ],
-								_fnGetCellData( oSettings, b, aDataSort[l], 'sort' )
+								aoData[b]._aSortData[ aDataSort[l] ]
 							);
 						
 							if ( iTest !== 0 )