added readme example to show inversion of sort order

1 files changed, 19 insertions, 0 deletions

diff --git a/README.md b/README.md
index f7d4f7a..a60ca4d 100644
--- a/README.md
+++ b/README.md
@@ -530,6 +530,25 @@ async.sortBy(['file1','file2','file3'], function(file, callback){
 });
 ```
 
+__Sort Order__
+
+By modifying the callback parameter the sorting order can be influenced:
+
+    //ascending order
+    async.sortBy([1,9,3,5], function(x, callback){
+        callback(err, x);
+    }, function(err,result){
+        //result callback
+    } );
+
+    //descending order
+    async.sortBy([1,9,3,5], function(x, callback){
+        callback(err, x*-1);    //<- x*-1 instead of x, turns the order around
+    }, function(err,result){
+        //result callback
+    } );
+
+
 ---------------------------------------
 
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