CODEWITHSUNDEEP
javascriptecmascript-6es6-promise
Mojimi
Mojimi

Reputation: 3161

How to use promise hierarchy while avoiding anti pattern?

I was trying to learn how to avoid the anti pattern as described here What is the explicit promise construction antipattern and how do I avoid it?

I started with some code on JSFiddle but it does not output what I expected..

function sum1(x){
    return new Promise(resolve => x+1)
}

function sum2(x){
  return sum1(x)
  .then(x => x+1);
}

function sum3(x){
  return sum2(x)
  .then(x => x+1)
}

sum3(1)
.then(console.log);

I would expect it to print 4 but it prints nothing

Upvotes: 0

Views: 38

Answers (2)

Ori Drori
Ori Drori

Reputation: 191976

You need to create a resolved promise by using Promise.resolve():

function sum1(x){
    return Promise.resolve(x+1)
}

function sum2(x){
  return sum1(x)
  .then(x => x+1);
}

function sum3(x){
  return sum2(x)
  .then(x => x+1)
}

sum3(1)
.then(console.log);

Upvotes: 3

Saad Mehmood
Saad Mehmood

Reputation: 731

you are doing it wrong in sum1. new Promise((resolve, reject) => {//code here}) takes function as argument

function sum1(x){
    return new Promise((resolve) => {
    	resolve(x + 1);
    })
}

function sum2(x){
  return sum1(x)
  .then(x => x+1);
}

function sum3(x){
  return sum2(x)
  .then(x => x+1)
}

sum3(1)
.then(res => console.log(res));

Upvotes: 2

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