added forever

3 files changed, 40 insertions, 0 deletions

diff --git a/README.md b/README.md
index 1716476..2c6e28b 100644
--- a/README.md
+++ b/README.md
@@ -91,6 +91,7 @@ So far its been tested in IE6, IE7, IE8, FF3.6 and Chrome 5. Usage:
 * [doWhilst](#doWhilst)
 * [until](#until)
 * [doUntil](#doUntil)
+* [forever](#forever)
 * [waterfall](#waterfall)
 * [compose](#compose)
 * [applyEach](#applyEach)
@@ -754,6 +755,14 @@ The inverse of async.whilst.
 
 Like doWhilst except the test is inverted. Note the argument ordering differs from `until`.
 
+---------------------------------------
+
+<a name="forever" />
+### forever(fn, callback)
+
+Calls the asynchronous function 'fn' repeatedly, in series, indefinitely.
+If an error is passed to fn's callback then 'callback' is called with the
+error, otherwise it will never be called.
 
 ---------------------------------------
 
diff --git a/lib/async.js b/lib/async.js
index 98f2127..b5bfc4c 100755
--- a/lib/async.js
+++ b/lib/async.js
@@ -910,6 +910,19 @@
         }
     };
 
+    async.forever = function (fn, callback) {
+        function next(err) {
+            if (err) {
+                if (callback) {
+                    return callback(err);
+                }
+                throw err;
+            }
+            fn(next);
+        }
+        next();
+    };
+
     // AMD / RequireJS
     if (typeof define !== 'undefined' && define.amd) {
         define([], function () {
diff --git a/test/test-async.js b/test/test-async.js
index cba6f4b..f9b9c08 100755
--- a/test/test-async.js
+++ b/test/test-async.js
@@ -66,6 +66,24 @@ function getFunctionsObject(call_order) {
     };
 }
 
+exports['forever'] = function (test) {
+    test.expect(1);
+    var counter = 0;
+    function addOne(callback) {
+        counter++;
+        if (counter === 50) {
+            return callback('too big!');
+        }
+        async.setImmediate(function () {
+            callback();
+        });
+    }
+    async.forever(addOne, function (err) {
+        test.equal(err, 'too big!');
+        test.done();
+    });
+};
+
 exports['applyEach'] = function (test) {
     test.expect(4);
     var call_order = [];