promise_mtd

promise_mtd

Set of methods allowing simplify work with Promises in cycle. Implementation forEach and map for working with array data unto whom need applied asynchronously function Method transform allows asynchronous iterations with array such as map, but also it can skip unnecessary data Implementation cycle while for using with Promise Method parallel allows run concurrently promises such as method Promise.all, but with limit.

npm i promise_mtd -S

foreach(Array, Function(el, index)) || forEach(Array, Function(el, index))

Foreach over promises serially

const promiseMtd = require('promise_mtd');
void async function () {
  await promiseMtd.forEach([ 300, 200, 100], async function (el, i) {
    return new Promise((resolve, reject) => {
      setTimeout(function() {
        console.log(el);
        resolve();
      }, el+i);
    });
  });
}();

map(Array, Function(el, index): Promise)

Map over promises serially

const promiseMtd = require('promise_mtd');
void async function () {
  let res = await promiseMtd.map([ 300, 200, 100], async function (el, i) {
    return new Promise((resolve, reject) => {
      setTimeout(function() {
        resolve(el*2);
      }, el*2);
    });
  });
  console.log(res); // [ 600, 400, 200 ]
}();

parallel(Array, Function(el, index))

Equalent Promise.all, but with limit

const promiseMtd = require('promise_mtd');
void async function() {
  try {
    await promiseMtd.parallel([ 3000, 3000, 3000, 2000, 2000, 2000, 1000], 3, async function(t, i) {
      return new Promise((resolve) => {
        // if (i === 4) {
        //   throw new Error('stop');
        // }
        setTimeout(() => {
          console.log(t);
          resolve();
        }, t);
      });
    });
  } catch (err) {
    console.log('Raise', err);
  }
}();

transform(Array, Function(el, index))

Iterate array and filter over promises

const promiseMtd = require('promise_mtd');
void async function() {
  let res = await promiseMtd.transform([ 1, 2, 3, 4 ], function (el, i) {
    if (el <= 2) {
      return new Promise((resolve) => {
        setTimeout(() => resolve({ el, i }), 1000);
      });
    }
  });
  console.log(res); // [ { el: 1, i: 0 }, { el: 2, i: 1 } ]
}();

while(condition: Function(): Boolean, Function)

While over promises serially

const promiseMtd = require('promise_mtd');
void async function() {
  let count = 5;
  await promiseMtd.while(() => count <= 0, async () => {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        console.log(count);
        count--;
        resolve();
      }, count * 1000);
    });
  })
  console.log(count); // 0
}();