diff --git a/src/order/appearance b/src/order/appearance
deleted file mode 100644
index a25a247..0000000
--- a/src/order/appearance
+++ /dev/null
@@ -1,10 +0,0 @@
-function stackOrderAppearance(series) {
-		var appearanceIndex = series.map(function(d,i){
-			for(var k = 0,n = d.length;k < n;++k){
-				if(d[k][1] > 0) break;
-			}
-			return [k, i];
-		});
-		appearanceIndex.sort(function(a,b){return a[0] - b[0];})
-		return appearanceIndex.map(function(d){return d[1]});
-}
diff --git a/src/order/appearance.js b/src/order/appearance.js
new file mode 100644
index 0000000..fb1f3d9
--- /dev/null
+++ b/src/order/appearance.js
@@ -0,0 +1,10 @@
+export default function(series) {
+  var appearanceIndex = series.map(function(d,i){
+    for(var k = 0, n = d.length;k < n;++k){
+      if(d[k][1] > 0) break;
+    }
+    return [k, i];
+  });
+  appearanceIndex.sort(function(a,b){return a[0] - b[0];})
+  return appearanceIndex.map(function(d){return d[1]});
+}