Delete all keys / versions from S3 bucket without API throtteling (flow control)

rmS3.js

var MAX_CONCURRENT_API_CALLS = 12;
var BUCKET = "bucket-name";

var AWS = require("aws-sdk");
var s3 = new AWS.S3();
var async = require("async");

var queue = async.queue(function(task, cb) {
        console.log(task.action);
        if (task.action === "list") {
                s3.listObjectVersions({
                        "Bucket": BUCKET,
                        "KeyMarker": task.nextKeyMarker,
                        "VersionIdMarker": task.nextVersionIdMarker
                }, function(err, data) {
                        if (err) {
                                cb(err);
                        } else {
                                var tasks = data.Versions.map(function(version) {
                                        return {"action": "delete", "key": version.Key, "versionId": version.VersionId};
                                });
                                queue.push(tasks);
                                if (data.IsTruncated === true) {
                                        queue.push({"action": "list", "nextKeyMarker": data.NextKeyMarker, "nextVersionIdMarker": data.NextVersionIdMarker});
                                }
                                cb();
                        }
                });
        } else if (task.action === "delete") {
                s3.deleteObject({
                        "Bucket": BUCKET,
                        "Key": task.key,
                        "VersionId": task.versionId
                }, cb);
        } else {
                cb(new Error("unsupported action " + task.action));
        }
}, MAX_CONCURRENT_API_CALLS);

queue.push({"action": "list"});