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waterfall.js 3.13 KiB
'use strict';
Object.defineProperty(exports, "__esModule", {
    value: true
});
var _once = require('./internal/once.js');
var _once2 = _interopRequireDefault(_once);
var _onlyOnce = require('./internal/onlyOnce.js');
var _onlyOnce2 = _interopRequireDefault(_onlyOnce);
var _wrapAsync = require('./internal/wrapAsync.js');
var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
var _awaitify = require('./internal/awaitify.js');
var _awaitify2 = _interopRequireDefault(_awaitify);
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
/**
 * 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 module:ControlFlow
 * @method
 * @category Control Flow
 * @param {Array} tasks - An array of [async functions]{@link AsyncFunction}
 * to run.
 * Each function should complete with any number of `result` values.
 * The `result` values 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]).
 * @returns {Promise} a promise, if a callback is omitted
 * @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'); * } */ function waterfall(tasks, callback) { callback = (0, _once2.default)(callback); if (!Array.isArray(tasks)) return callback(new Error('First argument to waterfall must be an array of functions')); if (!tasks.length) return callback(); var taskIndex = 0; function nextTask(args) { var task = (0, _wrapAsync2.default)(tasks[taskIndex++]); task(...args, (0, _onlyOnce2.default)(next)); } function next(err, ...args) { if (err === false) return; if (err || taskIndex === tasks.length) { return callback(err, ...args); } nextTask(args); } nextTask([]); } exports.default = (0, _awaitify2.default)(waterfall); module.exports = exports['default'];