diff --git a/js/com/cbl.js b/js/com/cbl.js
new file mode 100644
index 0000000..42cf75f
--- /dev/null
+++ b/js/com/cbl.js
@@ -0,0 +1,64 @@
+/**
+ **      ==============================
+ **       O           O      O   OOOO
+ **       O           O     O O  O   O
+ **       O           O     O O  O   O
+ **       OOOO   OOOO O     OOO  OOOO
+ **       O   O       O    O   O O   O
+ **       O   O       O    O   O O   O
+ **       OOOO        OOOO O   O OOOO
+ **      ==============================
+ **      Dr. Stefan Bosse http://www.bsslab.de
+ **
+ **      COPYRIGHT: THIS SOFTWARE, EXECUTABLE AND SOURCE CODE IS OWNED
+ **                 BY THE AUTHOR(S).
+ **                 THIS SOURCE CODE MAY NOT BE COPIED, EXTRACTED,
+ **                 MODIFIED, OR OTHERWISE USED IN A CONTEXT
+ **                 OUTSIDE OF THE SOFTWARE SYSTEM.
+ **
+ **    $AUTHORS:     Stefan Bosse
+ **    $INITIAL:     (C) 2006-2017 bLAB
+ **    $CREATED:     27-11-17 by sbosse.
+ **    $VERSION:     1.1.1
+ **
+ **    $INFO:
+ **
+ **  JavaScript Callback List
+ **
+ **  Assume there is a set of non-blocking IO operations with callbacks io1,io2,.., and there is a final
+ **  callback function that should be called after all io operations have finished.
+ **
+ **    $ENDOFINFO
+ */
+
+function CBL(callback) {
+  if (!(this instanceof CBL)) return new CBL(callback);
+  this.schedules=[];
+  this.callback=callback;
+}
+
+// Next schedule
+CBL.prototype.next = function (status) {
+  var f=this.schedules.shift();
+  // if (f) console.log('next '+f.toString())
+  if (f) {
+    f(this.next.bind(this),status);
+  } else if (this.callback) this.callback(status);
+}
+
+// Add next IO callback at the end of the list
+CBL.prototype.push = function (f) {
+  this.schedules.push(f);
+}
+
+// Execute CBL
+CBL.prototype.start = function () {
+  this.next();
+}
+
+// Add next IO callback at the top of the list
+CBL.prototype.top = function (f) {
+  this.schedules.unshift(f);
+}
+
+module.exports=CBL;