Asynchronous AntiPatterns

anti-patterns.js

// :)
// Let say you can perform these 3 actions in parallel, then you can run them 
// all at once and aggregate the result which is good
var p1 = addB(2, 3)
var p2 = addB(2, 3)
var p3 = addB(2, 3)
Promise.all([p1, p2, p3]).then(([r1, r2, r3]) => {
  console.log(r1, r2, r3)
})

// :(
// However if you do this it means you running them one after another so do not 
// abuse async/await. So I think async/await in this way is much more easier to be abused
async function main () {
  var r1 = await addB(2, 3);
  var r2 = await addB(2, 3);
  var r3 = await addB(2, 3);

  console.log(r1, r2, r3)
}

// :(
// Although the above code is exactly same as this which is bad too (note that we 
// assume you can perform the following actions in parallel)
var r1;
var r2;
var r3;
addB(2, 3)
  .then(result => {
    r1 = result;
    return addB(2, 3);
  })
  .then(result => {
    r2 = result;
    return addB(2, 3);
  })
  .then(result => {
    r3 = result;
  })
  .then(() => {
    console.log(r1, r2, r3)
  })


// :( :(
// Even worse than above code is to implement a nested promise so I don't 
// know why somebody do something like this
addB(2, 3)
  .then(result => {
    r1 = result;
    addB(2, 3).then(result => {
      r2 = result;
      addB(2, 3).then(result => {
        r3 = result;
      })
    })
  })