New: Absolute sorting plug-in

Keeps specific values at the top or bottom of the table when sorting by
that column.

sorting/absolute.js

@@ -0,0 +1,152 @@
+/**
+ * When sorting a DataTable you might find that you want to keep a specific
+ * item at the top or bottom of the table. For example when sorting a column
+ * of numbers, if a value is `null` or `N/A` you might want to keep it at the
+ * bottom of the table, regardless of if ascending or descending sorting is
+ * applied. This plug-in provides that ability.
+ *
+ * You must call the `$.fn.dataTable.absoluteOrder` with information about the
+ * value(s) you wish to make absolute in the sorting order and store the
+ * returned value, assigning it to the `columns.type` option for the column
+ * you wish this sorting to be applied to.
+ *
+ * For number based columns a `$.fn.dataTable.absoluteOrderNumber` function is
+ * also available.
+ *
+ * @name Absolute sorting
+ * @summary Keep one or more items at the top and/or bottom of a table when sorting
+ * @author [Allan Jardine](//datatables.net)
+ * @depends DataTables 1.10+
+ *
+ * @example
+ *    var namesType = $.fn.dataTable.absoluteOrder( [
+ *      { value: '', position: 'top' }
+ *    ] );
+ *    
+ *    var numbersType = $.fn.dataTable.absoluteOrderNumber( [
+ *      { value: 'N/A', position: 'bottom' }
+ *    ] );
+ *    
+ *    $('#example').DataTable( {
+ *      columnDefs: [
+ *        { type: namesType, targets: 0 },
+ *        { type: numbersType, targets: 1 }
+ *      ]
+ *    } );
+ */
+
+(function (factory) {
+	if (typeof define === "function" && define.amd) {
+		define(["jquery", "datatables.net"], factory);
+	} else {
+		factory(jQuery);
+	}
+}(function ($) {
+
+// Unique value allowing multiple absolute ordering use cases on a single page.
+var _unique = 0;
+
+// Function to encapsulate code that is common to both the string and number
+// ordering plug-ins.
+var _setup = function ( values ) {
+	if ( ! $.isArray( values ) ) {
+		values = [ values ];
+	}
+
+	var o = {
+		name: 'absoluteOrder'+(_unique++),
+		alwaysTop: {},
+		alwaysBottom: {}
+	};
+
+	// In order to provide performance, the symbols that are to be looked for
+	// are stored as parameter keys in an object, allowing O(1) lookup, rather
+	// than O(n) if it were in an array.
+	for ( var i=0, ien=values.length ; i<ien ; i++ ) {
+		var conf = values[i];
+
+		if ( typeof conf === 'string' ) {
+			o.alwaysTop[ conf ] = true;
+		}
+		else if ( conf.position === undefined || conf.position === 'top' ) {
+			o.alwaysTop[ conf.value ] = true;
+		}
+		else {
+			o.alwaysBottom[ conf.value ] = true;
+		}
+	}
+
+	// Ascending ordering method
+	o.asc = function ( a, b, isNumber ) {
+		if ( o.alwaysTop[ a ] || o.alwaysBottom[ b ] ) {
+			return -1;
+		}
+		else if ( o.alwaysBottom[ a ] || o.alwaysTop[ b ] ) {
+			return 1;
+		}
+
+		if ( isNumber ) {
+			// Cast as a number if required
+			if ( typeof a === 'string' ) {
+				a = a.replace(/[^\d\-\.]/g) * 1;
+			}
+			if ( typeof b === 'string' ) {
+				b = b.replace(/[^\d\-\.]/g) * 1;
+			}
+		}
+
+		return ((a < b) ? -1 : ((a > b) ? 1 : 0));
+	};
+
+	// Descending ordering method
+	o.desc = function ( a, b, isNumber ) {
+		if ( o.alwaysTop[ a ] || o.alwaysBottom[ b ] ) {
+			return -1;
+		}
+		else if ( o.alwaysBottom[ a ] || o.alwaysTop[ b ] ) {
+			return 1;
+		}
+
+		if ( isNumber ) {
+			if ( typeof a === 'string' ) {
+				a = a.replace(/[^\d\-\.]/g) * 1;
+			}
+			if ( typeof b === 'string' ) {
+				b = b.replace(/[^\d\-\.]/g) * 1;
+			}
+		}
+
+		return ((a < b) ? 1 : ((a > b) ? -1 : 0));
+	};
+
+	return o;
+};
+
+// String based ordering
+$.fn.dataTable.absoluteOrder = function ( values ) {
+	var conf = _setup( values );
+
+	$.fn.dataTable.ext.type.order[ conf.name+'-asc' ] = conf.asc;
+	$.fn.dataTable.ext.type.order[ conf.name+'-desc' ] = conf.desc;
+
+	// Return the name of the sorting plug-in that was created so it can be used
+	// with the `columns.type` parameter. There is no auto-detection here.
+	return conf.name;
+};
+
+// Number based ordering - strips out everything but the number information
+$.fn.dataTable.absoluteOrderNumber = function ( values ) {
+	var conf = _setup( values );
+
+	$.fn.dataTable.ext.type.order[ conf.name+'-asc' ] = function ( a, b ) {
+		return conf.asc( a, b, true );
+	};
+	$.fn.dataTable.ext.type.order[ conf.name+'-desc' ] = function ( a, b ) {
+		return conf.asc( a, b, true );
+	};
+
+	return conf.name;
+};
+
+
+}));