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import noop from 'lodash/noop';
/**
* Like [`whilst`]{@link module:ControlFlow.whilst}, except the `test` is an asynchronous function that
* is passed a callback in the form of `function (err, truth)`. If error is
* passed to `test` or `fn`, the main callback is immediately called with the
* value of the error.
*
* @name during
* @static
* @memberOf module:ControlFlow
* @method
* @see [async.whilst]{@link module:ControlFlow.whilst}
* @category Control Flow
* @param {Function} test - asynchronous truth test to perform before each
* execution of `fn`. Invoked with (callback).
* @param {Function} fn - A function which is called each time `test` passes.
* The function is passed a `callback(err)`, which must be called once it has
* completed with an optional `err` argument. Invoked with (callback).
* @param {Function} [callback] - A callback which is called after the test
* function has failed and repeated execution of `fn` has stopped. `callback`
* will be passed an error, if one occured, otherwise `null`.
* @example
*
* var count = 0;
*
* async.during(
* function (callback) {
* return callback(null, count < 5);
* },
* function (callback) {
* count++;
* setTimeout(callback, 1000);
* },
* function (err) {
* // 5 seconds have passed
* }
* );
*/
export default function during(test, fn, callback) {
callback = callback || noop;
function next(err) {
if (err) return callback(err);
test(check);
}
function check(err, truth) {
if (err) return callback(err);
if (!truth) return callback(null);
fn(next);
}
test(check);
}
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