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jthoms1/waterfall.ts

Created September 4, 2018 19:08
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  1. jthoms1 created this gist Sep 4, 2018.
    24 changes: 24 additions & 0 deletions waterfall.ts
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,24 @@

    function waterFallExec<T, S>(listOfItems: T[], func: (item: T) => Promise<S>): Promise<S[]> {
    const results: S[] = []
    return listOfItems.reduce(function (lastPromise, item) {
    return lastPromise.then(function (res) {
    return func(item).then(function (result) {
    res.push(result);
    return res;
    });
    });
    }, Promise.resolve(results));
    }



    const promiseOfResults = waterFallExec(['1', '2', '3'], (item) => {
    return Promise.resolve(
    parseInt(item, 10)
    );
    });

    promiseOfResults.then((results) => {
    console.log(results);
    })