3 Object.defineProperty(exports, "__esModule", {
6 exports.default = ensureAsync;
8 var _setImmediate = require('./internal/setImmediate');
10 var _setImmediate2 = _interopRequireDefault(_setImmediate);
12 var _initialParams = require('./internal/initialParams');
14 var _initialParams2 = _interopRequireDefault(_initialParams);
16 function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
19 * Wrap an async function and ensure it calls its callback on a later tick of
20 * the event loop. If the function already calls its callback on a next tick,
21 * no extra deferral is added. This is useful for preventing stack overflows
22 * (`RangeError: Maximum call stack size exceeded`) and generally keeping
23 * [Zalgo](http://blog.izs.me/post/59142742143/designing-apis-for-asynchrony)
28 * @memberOf module:Utils
31 * @param {Function} fn - an async function, one that expects a node-style
32 * callback as its last argument.
33 * @returns {Function} Returns a wrapped function with the exact same call
34 * signature as the function passed in.
37 * function sometimesAsync(arg, callback) {
39 * return callback(null, cache[arg]); // this would be synchronous!!
41 * doSomeIO(arg, callback); // this IO would be asynchronous
45 * // this has a risk of stack overflows if many results are cached in a row
46 * async.mapSeries(args, sometimesAsync, done);
48 * // this will defer sometimesAsync's callback if necessary,
49 * // preventing stack overflows
50 * async.mapSeries(args, async.ensureAsync(sometimesAsync), done);
52 function ensureAsync(fn) {
53 return (0, _initialParams2.default)(function (args, callback) {
55 args.push(function () {
56 var innerArgs = arguments;
58 (0, _setImmediate2.default)(function () {
59 callback.apply(null, innerArgs);
62 callback.apply(null, innerArgs);
69 module.exports = exports['default'];