Row comparator

docs/api/column/inputs.md

@@ -23,8 +23,13 @@ The width of the column by default in pixels. Default value: `150`
 The column can be resized manually by the user. Default value: `true`
 
 ### `comparator`
-Custom sort comparator, used to apply custom sorting via client-side. See 
-[MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort) for more info.
+Custom sort comparator, used to apply custom sorting via client-side.
+Function receives five parameters, namely values and rows of items to be sorted as well as direction of the sort ('asc'|'desc'):
+```
+(valueA, valueB, rowA, rowB, sortDirection) => -1|0|1
+```
+NOTE: Compare can be a standard JS comparison function (a,b) => -1|0|1 as additional parameters are silently ignored.
+See [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort) for more info.
 
 ### `sortable`: `boolean`
 Sorting of the row values by this column. Default value: `true`

src/components/datatable.component.ts

@@ -394,7 +394,7 @@ export class DatatableComponent implements OnInit, DoCheck, AfterViewInit {
    *      return row.name !== 'Ethel Price';
    *    }
    */
-  @Input() displayCheck: (row, column?, value?) => boolean;
+  @Input() displayCheck: (row: any, column?: any, value?: any) => boolean;
 
   /**
    * A boolean you can use to set the detault behaviour of rows and groups

src/utils/sort.ts

@@ -75,16 +75,25 @@ export function sortRows(rows: any[], columns: any[], dirs: SortPropDir[]): any[
     };
   });
 
-  return temp.sort(function(a: any, b: any) {
+  return temp.sort(function(rowA: any, rowB: any) {
 
     for(const cachedDir of cachedDirs) {
+      // Get property and valuegetters for column to be sorted
       const { prop, valueGetter } = cachedDir;
-      const propA = valueGetter(a, prop);
-      const propB = valueGetter(b, prop);
+      // Get A and B cell values from rows based on properties of the columns
+      const propA = valueGetter(rowA, prop);
+      const propB = valueGetter(rowB, prop);
 
+      // Compare function gets five parameters:
+      // Two cell values to be compared as propA and propB
+      // Two rows corresponding to the cells as rowA and rowB
+      // Direction of the sort for this column as SortDirection
+      // Compare can be a standard JS comparison function (a,b) => -1|0|1
+      // as additional parameters are silently ignored. The whole row and sort
+      // direction enable more complex sort logic.
       const comparison = cachedDir.dir !== SortDirection.desc ?
-        cachedDir.compareFn(propA, propB) :
-        -cachedDir.compareFn(propA, propB);
+        cachedDir.compareFn(propA, propB, rowA, rowB, cachedDir.dir) :
+        -cachedDir.compareFn(propA, propB, rowA, rowB, cachedDir.dir);
 
       // Don't return 0 yet in case of needing to sort by next property
       if (comparison !== 0) return comparison;