Yet another post about async/await and promises

examples.js

// https://dev.to/viniciuskneves/yet-another-post-about-asyncawait-and-promises-49gg

// Example 1
function doSomething() {
  return Promise.resolve('#2');
}

const promise = doSomething().then(console.log);

console.log('#1');

// Example 2
(async function () {
  async function doSomething() {
    return '#2';
  }

  const result = await doSomething();
  console.log(result);

  console.log('#1');
})();

// Example 3
function doSomething() {
  return Promise.resolve('#2');
}

const promise = doSomething().then(data => {
  console.log(data);

  console.log('#1');
});

// Example 4
(async function () {
  function doSomething() {
    return Promise.resolve('#2');
  }

  const result = await doSomething();
  console.log(result);

  console.log('#1');
})();

// Example 5
(async function () {
  async function doSomething() {
    return '#2';
  }

  const result = doSomething().then(console.log);

  console.log('#1');
})();

// Example 6
(async function () {
  function doSomethingPromise() {
    return Promise.resolve('#2');
  }

  async function doSomethingAsync() {
    return '#2';
  }

  const somePromise = doSomethingPromise();
  const someAsync = doSomethingAsync();

  console.log(somePromise);
  console.log(someAsync);
})();

// Example 7
/*
async function myFunction(...params) {
 const value1 = await someFunction1();
 const value2 = await someFunction2(...params);

 // The following code needs to sync
 const whatNow = async () => {
   await value1.forEach(async v1 => {
     someFunction3(v1);
     someFunction4(v1);
     value2.forEach(v2 => {
       someFunction5(v1, v2);
     });
   });
 }

 whatNow();
} 
*/

(async function() {
  async function someFunction1() {
    return ['f1_1', 'f1_2', 'f1_3'];
  }

  async function someFunction2() {
    return ['f2_1', 'f2_2', 'f2_3'];
  }

  async function someFunction3(v1) {
    return `f3+${v1}`;
  }

  async function someFunction4(v1) {
    return `f4+${v1}`;
  }

  async function someFunction5(v1, v2) {
    return `f5+${v1}+${v2}`;
  }

  const [value1, value2] = await Promise.all([someFunction1(), someFunction2()]);
  const promises = flatten(value1.map(v1 => [
    someFunction3(v1),
    someFunction4(v1),
    value2.map(v2 => someFunction5(v1, v2)),
  ]));

  const result = await Promise.all(promises);

  console.log(result);

})();

// https://stackoverflow.com/questions/10865025/merge-flatten-an-array-of-arrays-in-javascript
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flatMap
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flat
function flatten(arr) {
  return arr.reduce(function (flat, toFlatten) {
    return flat.concat(Array.isArray(toFlatten) ? flatten(toFlatten) : toFlatten);
  }, []);
}