diff --git a/assets/sprite-pointer_tail.png b/assets/sprite-pointer_tail.png
new file mode 100644
index 0000000..f1919bf
Binary files /dev/null and b/assets/sprite-pointer_tail.png differ
diff --git a/js/1-jsloader.js b/js/1-jsloader.js
index d457c0a..fa6732a 100644
--- a/js/1-jsloader.js
+++ b/js/1-jsloader.js
@@ -10,10 +10,10 @@
         return;
     }
 
-    var scriptManager= {};
-    scriptManager.loadingcount=0;
+    var ScriptManager= {};
+    ScriptManager.loading_count=0;
 
-    scriptManager.loadjs=async function(pth) {
+    ScriptManager.loadjs=async function(pth) {
         var resolve;
         var reject;
         var ret=new Promise(function(s, r) {
@@ -27,7 +27,7 @@
                 return;
             }
             removelisteners();
-            scriptManager.loadingcount--;
+            ScriptManager.loading_count--;
             if(xhr.status!=200) {
                 onfail();
                 return;
@@ -72,19 +72,19 @@
         xhr.open("GET", pth, true);
         xhr.send();
 
-        scriptManager.loadingcount++;
+        ScriptManager.loading_count++;
         return ret;
     };
 
-    scriptManager.isDone=function() {
-        return scriptManager.loadingcount==0;
+    ScriptManager.isDone=function() {
+        return ScriptManager.loading_count==0;
     };
 
-    scriptManager.waitAll=async function() {
+    ScriptManager.waitAll=async function() {
         return new Promise(function(resolve, reject) {
             var i;
             i=setInterval(function() {
-                if(scriptManager.loadingcount==0) {
+                if(ScriptManager.loading_count==0) {
                     clearInterval(i);
                     resolve();
                 }
@@ -92,5 +92,5 @@
         });
     };
 
-    window.scriptManager=scriptManager;
+    window.ScriptManager=ScriptManager;
 })();
diff --git a/js/2-jsloadentry.js b/js/2-jsloadentry.js
index 8c47bd1..ed2906c 100644
--- a/js/2-jsloadentry.js
+++ b/js/2-jsloadentry.js
@@ -1,24 +1,25 @@
 //jsloadentry.js
 
 (async function() {
-    if(!(typeof scriptManager=="object"&&"loadjs" in scriptManager)) {
+    if(!(typeof ScriptManager=="object"&&"loadjs" in ScriptManager)) {
         if(typeof loadfail=="function") {
-            loadfail("jsloadentry.js: scriptManager.loadjs is not defined");
+            loadfail("jsloadentry.js: ScriptManager.loadjs is not defined");
         } else {
-            window.alert("jsloadentry.js: scriptManager.loadjs is not defined");
+            window.alert("jsloadentry.js: ScriptManager.loadjs is not defined");
         }
         return;
     }
 
-    scriptManager.loadjs("./js/libpolyfill.requestAnimationFrame.js");
-    scriptManager.loadjs("./js/libutil.js");
-    scriptManager.loadjs("./js/libcubicbezier.js");
-    scriptManager.loadjs("./js/libwebglcheck.js");
-    scriptManager.loadjs("./js/libpixi_v891gl.dev.min.js");
-    //scriptManager.loadjs("./js/libpixi_v891gl.prod.min.js");
-    await scriptManager.waitAll();
-    await scriptManager.loadjs("./js/libtransition.js");
-    await scriptManager.loadjs("./js/libmain.js");
-    scriptManager.loadjs("./js/libpointerfx.js");
-    await scriptManager.waitAll();
+    ScriptManager.loadjs("./js/libpolyfill.requestAnimationFrame.js");
+    ScriptManager.loadjs("./js/libutil.js");
+    ScriptManager.loadjs("./js/libcubicbezier.js");
+    ScriptManager.loadjs("./js/libwebglcheck.js");
+    ScriptManager.loadjs("./js/libpixi_v891gl.dev.min.js");
+    //ScriptManager.loadjs("./js/libpixi_v891gl.prod.min.js");
+    ScriptManager.loadjs("./js/libassetloader.js");
+    await ScriptManager.waitAll();
+    await ScriptManager.loadjs("./js/libtransition.js");
+    await ScriptManager.loadjs("./js/libmain.js");
+    ScriptManager.loadjs("./js/libpointerfx.js");
+    await ScriptManager.waitAll();
 })();
\ No newline at end of file
diff --git a/js/libassetloader.js b/js/libassetloader.js
new file mode 100644
index 0000000..07db92b
--- /dev/null
+++ b/js/libassetloader.js
@@ -0,0 +1,112 @@
+//libassetloader.js
+
+(async function() {
+    if(typeof XMLHttpRequest!="function") {
+        if(typeof loadfail=="function") {
+            loadfail("libassetloader.js: XMLHttpRequest(type of "+(typeof XMLHttpRequest)+") is not a function");
+        } else {
+            window.alert("libassetloader.js: XMLHttpRequest(type of "+(typeof XMLHttpRequest)+") is not a function");
+        }
+        return;
+    }
+    if(typeof Blob!="function") {
+        if(typeof loadfail=="function") {
+            loadfail("libassetloader.js: Blob(type of "+(typeof Blob)+") is not a function");
+        } else {
+            window.alert("libassetloader.js: Blob(type of "+(typeof Blob)+") is not a function");
+        }
+        return;
+    }
+    if(typeof URL!="function") {
+        if(typeof loadfail=="function") {
+            loadfail("libassetloader.js: URL(type of "+(typeof URL)+") is not a function");
+        } else {
+            window.alert("libassetloader.js: URL(type of "+(typeof URL)+") is not a function");
+        }
+        return;
+    }
+
+    var AssetManager= {};
+
+    // map http url -> blob url
+    AssetManager.loadedAssets= {};
+
+    AssetManager.loading_count=0;
+
+    AssetManager.loadWithCache=async function(pth) {
+        if(pth in AssetManager.loadedAssets) {
+            return Promise.resolve(AssetManager.loadedAssets[pth]);
+        }
+        return AssetManager.do_fetch_res(pth);
+    };
+
+    AssetManager.do_fetch_res=async function(pth) {
+        var resolve;
+        var reject;
+        var ret=new Promise(function(s, r) {
+            resolve=s;
+            reject=r;
+        });
+        var xhr=new XMLHttpRequest();
+
+        xhr.responseType = "blob";
+
+        var onreadystatechange=async function() {
+            if(xhr.readyState!=XMLHttpRequest.DONE) {
+                return;
+            }
+            removelisteners();
+            AssetManager.loading_count--;
+            if(xhr.status!=200) {
+                onfail();
+                return;
+            }
+            AssetManager.loadedAssets[pth]=URL.createObjectURL(xhr.response);
+            console.debug("asset "+pth+" loaded from source.");
+            resolve(AssetManager.loadedAssets[pth]);
+            return;
+        };
+
+        var onfail=function() {
+            removelisteners();
+            xhr.abort();
+            window.loadfail("asset "+pth+" load failed");
+            reject("asset "+pth+" load failed");
+        };
+
+        var removelisteners=function() {
+            xhr.removeEventListener("readystatechange", onreadystatechange);
+            xhr.removeEventListener("error", onfail);
+            xhr.removeEventListener("abort", onfail);
+        };
+
+        xhr.addEventListener("readystatechange", onreadystatechange);
+        xhr.addEventListener("error", onfail);
+        xhr.addEventListener("abort", onfail);
+
+        xhr.open("GET", pth, true);
+        xhr.send();
+
+        AssetManager.loading_count++;
+        return ret;
+    };
+
+    AssetManager.isDone=function() {
+        return AssetManager.loading_count==0;
+    };
+
+    AssetManager.waitAll=async function() {
+        return new Promise(function(resolve, reject) {
+            var i;
+            i=setInterval(function() {
+                if(AssetManager.loading_count==0) {
+                    clearInterval(i);
+                    resolve();
+                }
+            }, 100);
+        });
+    };
+
+    window.AssetManager=AssetManager;
+
+})();
\ No newline at end of file
diff --git a/js/libmain.js b/js/libmain.js
index 2734fb4..bf22c72 100644
--- a/js/libmain.js
+++ b/js/libmain.js
@@ -1,3 +1,5 @@
+//libmain.js
+
 return (async function() {
     if(typeof PIXI!="object") {
         if(typeof loadfail=="function") {