--- a/board.js	Sat Feb 06 14:34:51 2016 +0200
+++ b/board.js	Sun Aug 07 23:14:11 2016 +0300
@@ -71,6 +71,22 @@
             cnt++;
     return cnt;
 }
+/** Put random value to free cell uniformly. */
+BoardArr.prototype.rnd = function(val) {
+    var brd = this.brd;
+    var idx;
+    var free = 0;
+    for (var i = 0; i < 16; i++) {
+        if (brd[idx] === 0) {
+            free++;
+            if (Math.random()*free < 1)
+                idx = i;
+        }
+    }
+    if (free === 0)
+        throw new Error('There are no free space...');
+    brd[idx] = val;
+}
 BoardArr.prototype.score = function() {
     var score = 0;
     for (var i = 0; i < 16; i++) {
@@ -178,6 +194,24 @@
                 cnt++;
     return cnt;
 }
+/** Put random value to free cell uniformly. */
+BoardArr2d.prototype.rnd = function(val) {
+    var brd = this.brd;
+    var xi, xj;
+    var free = 0;
+    for (var i = 0; i < 4; i++)
+        for (var j = 0; j < 4; j++)
+            if (this.brd[i][j] === 0) {
+                free++;
+                if (Math.random()*free < 1) {
+                    xi = i;
+                    xj = j;
+                }
+            }
+    if (free === 0)
+        throw new Error('There are no free space...');
+    brd[xi][xj] = val;
+}
 BoardArr2d.prototype.score = function() {
     var score = 0;
     for (var i = 0; i < 4; i++) {