asyncc/lib/series.js

Just asynchronous patterns

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports["default"] = series;
var _setImmediate2 = require("./_setImmediate");
/**
* Run `tasks` callback functions in series
* The function breaks after the first error encountered and calls optional
* `callback` function
*
* @name series
* @memberOf module:serial
* @static
* @method
* @param {Array} tasks - Array of callback functions of type `function (cb: Function)`
* @param {Function} [callback] - optional callback function called by last
* terminating function from `tasks`, needs to be of type
* `function (err: Error, res: Array<any>)`
*
* @example
* series([
*   (cb) => { cb(null, 1) },
*   (cb) => { cb('error', 2) }, // breaks on first error
*   (cb) => { cb(null, 3) },
* ], (err, res) => {
*   //> err = 'error'
*   //> res = [1, 2]
* })
*/
function series(tasks, callback) {
  var length = tasks.length;
  var results = [];
  var i = 0;
  if (length === 0) {
    callback(null, []);
    return;
  }
  run();
  function run() {
    tasks[i++](cb);
  }
  function cb(err, res) {
    results.push(res);
    /* istanbul ignore else */
    if (err || length === i) {
      callback && callback(err, results);
    } else if (i < length) {
      (0, _setImmediate2._setImmediate)(function () {
        // prevent RangeError: Maximum call stack size exceeded for sync tasks
        run();
      });
    }
  }
}