doWhilst.js

import onlyOnce from './internal/onlyOnce.js'
import wrapAsync from './internal/wrapAsync.js'
import awaitify from './internal/awaitify.js'
/**
 * The post-check version of [`whilst`]{@link module:ControlFlow.whilst}. To reflect the difference in
 * the order of operations, the arguments `test` and `iteratee` are switched.
 *
 * `doWhilst` is to `whilst` as `do while` is to `while` in plain JavaScript.
 *
 * @name doWhilst
 * @static
 * @memberOf module:ControlFlow
 * @method
 * @see [async.whilst]{@link module:ControlFlow.whilst}
 * @category Control Flow
 * @param {AsyncFunction} iteratee - A function which is called each time `test`
 * passes. Invoked with (callback).
 * @param {AsyncFunction} test - asynchronous truth test to perform after each
 * execution of `iteratee`. Invoked with (...args, callback), where `...args` are the
 * non-error args from the previous callback of `iteratee`.
 * @param {Function} [callback] - A callback which is called after the test
 * function has failed and repeated execution of `iteratee` has stopped.
 * `callback` will be passed an error and any arguments passed to the final
 * `iteratee`'s callback. Invoked with (err, [results]);
 * @returns {Promise} a promise, if no callback is passed
 */
function doWhilst(iteratee, test, callback) {
    callback = onlyOnce(callback);
    var _fn = wrapAsync(iteratee);
    var _test = wrapAsync(test);
    var results
    function next(err, ...args) {
        if (err) return callback(err);
        if (err === false) return;
        results = args
        _test(...args, check);
    }
    function check(err, truth) {
        if (err) return callback(err);
        if (err === false) return;
        if (!truth) return callback(null, ...results);
        _fn(next);
    }
    return check(null, true);
}
export default awaitify(doWhilst, 3)