Promise all

promise-all.ts

/* 
 * If used Promise all first error will go to catch block
 *
 * If no error occurs then the resolved values will be an array
   with exact sequence of promise here e.g if run Promise.all([p1, p2, p3])
   output: [ 'one', 'two', 'three' ]
 * 
 * If there is a setTimeout after all setTimeout execution will be done
 * 
 * If there is a setTimeout, setImmediate or setTimeout 0 thoose will be executed after next tick
*/

const p1 = new Promise((resolve, reject) => {
  setTimeout(() => resolve('one'), 1000);
});
const p2 = new Promise((resolve, reject) => {
  setTimeout(() => resolve('two'), 2000);
});
const p3 = new Promise((resolve, reject) => {
  setTimeout(() => resolve('three'), 3000);
});
const p4 = new Promise((resolve, reject) => {
  setTimeout(() => reject(new Error('p4')), 4000);
});
const p5 = new Promise((resolve, reject) => {
  reject(new Error('p5'));
});
const p6 = new Promise((resolve, reject) => {
  reject(new Error('p6'));
});

// Using .catch:
Promise.all([p1, p2, p3, p4, p5, p6, Promise.reject('p7')])
  .then(values => {
    console.log(values);
  })
  .catch(error => {
    console.error(error);
  });