Create Recursive In Promise instead of calling many times

Question

I have this code:

var arrMultiplication = function(arr1, arr2) {
  return new Promise(function(resolve, reject) {

    if ( arr1.length ==arr2.length ) {
        temp =new Array();
        for(var i=0;i<arr1.length;i++){
        temp.push(arr1[i]*arr2[i]);
      }
      resolve(temp);
    } else {
      reject(Error("Promise Rejected"));
    }
  });
}
//[1,2,5], [1,2,0],[2,2,2].[1,2,3]
var A=[1,2,5];
var B=[1,2,0];
var C=[2,2,2];
var D=[1,2,3];
arrMultiplication(A,B).then(function(result){
    arrMultiplication(C,result).then(function(result){
    arrMultiplication(D,result).then(function(result){
        alert(result);
    });
  });
});

JSfiddle

How can I do it simpler instead of calling promise many times IF i have A B C D E F as arrays it will complex with this way. how to make it easier.

Why do you even use Promises anyway? There's no async code in there — Szab
– Szab, Commented Nov 15, 2018 at 15:53
I need to understand simplest way to use it, instead of coding complex coding,i would appreciate hints <3 — Muath
– Muath, Commented Nov 15, 2018 at 15:59

Ariel · Accepted Answer · 2018-11-15 15:59:57Z

1

Although i agree with @szab comment that you don't need Promises here, in general terms you can use reduce to chain n-length promises.

Example:

var arrMultiplication = function(arr1, arr2) {
      return new Promise(function(resolve, reject) {
        
        if ( arr1.length ==arr2.length ) {
        	temp =new Array();
        	for(var i=0;i<arr1.length;i++){
          	temp.push(arr1[i]*arr2[i]);
          }
          resolve(temp);
        } else {
          reject(Error("Promise Rejected"));
        }
      });
    }
    //[1,2,5], [1,2,0],[2,2,2].[1,2,3]
    var A=[1,2,5];
    var B=[1,2,0];
    var C=[2,2,2];
    var D=[1,2,3];
    var allArrays = [A, B, C, D];
    
    const multiplicationsPromise = allArrays.reduce((resultPromise, currentArray) => {
    	return resultPromise.then(result => arrMultiplication(result, currentArray))	
    }, Promise.resolve([1,1,1]))
    
    multiplicationsPromise.then(result => alert(result));

Working fiddle here

answered Nov 15, 2018 at 15:59

Ariel

1,4368 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Muath Over a year ago

i agree with @szab too no need for promise here but im asking about logic that can be, and i think you answer explains everything <3

Collectives™ on Stack Overflow

Create Recursive In Promise instead of calling many times

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related