@plantinformatics/vcf-genotype-brapi/src/utils/data/promises.js

Client and server functions to access genotype data from VCF via a custom web API and BrAPI

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// copied from @plantinformatics/pretzel frontend/app/utils/common/promises.js d04ce254

export { reduceInSeries };
/** Reduce the array to a promise; map each array element to a promise using
 * elt2PromiseFn, in series (not in parallel).
 * @param array
 * @param elt2PromiseFn (previousResult, element) -> promise
 * @param starting_promise  Start after this initial promise yields
 * Defaults to Promise.resolve() if undefined.
 */
function reduceInSeries(array, elt2PromiseFn, starting_promise) {
  /** based on ensureCounts() in lb4app/lb3app/common/utilities/block-features.js
   * and also https://stackoverflow.com/a/21372567 user663031
   * @param previousP head of chain of promises
   * @param previous result value yielded by previousP
   */
  const promise = array.reduce(
    (previousP, currentElement) => previousP.then(
      (previous) => elt2PromiseFn(previous, currentElement)),
    starting_promise ?? Promise.resolve());
  return promise;
}

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/** Map array to an array of promises, which are the results of calling
 * elt2PromiseFn() on each element of the array, in series.
 * elt2PromiseFn() returns a promise.
 * The result promise is used to perform each call to elt2PromiseFn() in series
 * instead of in parallel.
 * @param {Array} array
 * @param  {function(any, number): Promise} elt2PromiseFn
 * The signature of elt2PromiseFn() is (element, i) => promise.
 */
export function mapInSeries(array, elt2PromiseFn) {
  let promise = Promise.resolve();
  /** Wrap elt2PromiseFn() to provide series execution. */
  function seriesWrap(elt, i) {
    promise = promise.then(result => elt2PromiseFn(elt, i));
    return promise;
  }
  const
  allP = Promise.all(array.map(seriesWrap));
  return allP;
}

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