1 files changed, 55 insertions, 0 deletions
diff --git a/lib/waterfall.js b/lib/waterfall.js
index aaed2ee..c76b332 100644
--- a/lib/waterfall.js
+++ b/lib/waterfall.js
@@ -7,6 +7,61 @@ import rest from 'lodash/rest';
 
 import onlyOnce from './internal/onlyOnce';
 
+/**
+ * Runs the `tasks` array of functions in series, each passing their results to
+ * the next in the array. However, if any of the `tasks` pass an error to their
+ * own callback, the next function is not executed, and the main `callback` is
+ * immediately called with the error.
+ *
+ * @name waterfall
+ * @static
+ * @memberOf async
+ * @category Control Flow
+ * @param {Array} tasks - An array of functions to run, each function is passed
+ * a `callback(err, result1, result2, ...)` it must call on completion. The
+ * first argument is an error (which can be `null`) and any further arguments
+ * will be passed as arguments in order to the next task.
+ * @param {Function} [callback] - An optional callback to run once all the
+ * functions have completed. This will be passed the results of the last task's
+ * callback. Invoked with (err, [results]).
+ * @example
+ *
+ * async.waterfall([
+ *     function(callback) {
+ *         callback(null, 'one', 'two');
+ *     },
+ *     function(arg1, arg2, callback) {
+ *         // arg1 now equals 'one' and arg2 now equals 'two'
+ *         callback(null, 'three');
+ *     },
+ *     function(arg1, callback) {
+ *         // arg1 now equals 'three'
+ *         callback(null, 'done');
+ *     }
+ * ], function (err, result) {
+ *     // result now equals 'done'
+ * });
+ *
+ * // Or, with named functions:
+ * async.waterfall([
+ *     myFirstFunction,
+ *     mySecondFunction,
+ *     myLastFunction,
+ * ], function (err, result) {
+ *     // result now equals 'done'
+ * });
+ * function myFirstFunction(callback) {
+ *     callback(null, 'one', 'two');
+ * }
+ * function mySecondFunction(arg1, arg2, callback) {
+ *     // arg1 now equals 'one' and arg2 now equals 'two'
+ *     callback(null, 'three');
+ * }
+ * function myLastFunction(arg1, callback) {
+ *     // arg1 now equals 'three'
+ *     callback(null, 'done');
+ * }
+ */
 export default  function(tasks, cb) {
     cb = once(cb || noop);
     if (!isArray(tasks)) return cb(new Error('First argument to waterfall must be an array of functions'));