CODEWITHSUNDEEP
javascriptarraysfor-loopreturnundefined
tyson
tyson

Reputation: 3

Function will log value but return undefined

The function below will log the value of newData but returns undefined when called. Does anyone know why this might be? Also, any feedback on the function itself would be greatly appreciated!

export const filterByDateTimeRange = (data=[{}], timeKey=[], startTime=moment(), stopTime=moment()) => {
  let newData = [];
  let i = 0;
  for(const item of data) {
    let time;
    let index = 0
    timeKey.map(key => {
      time ? time = time[key] : time = item[key];
      index++
      if(index === timeKey.length) {
        if(moment(time).isBetween(startTime, stopTime, undefined, '[)')) {
          newData.push(item)
        };
        i++;
        if(i === data.length) {
          console.log(newData);
          return (newData);
        }
      }
    })
  }
}

Upvotes: 0

Views: 46

Answers (2)

IrkenInvader
IrkenInvader

Reputation: 4050

The map function is usually used to transform a collection and store the results, for example:

var squares = [2, 3, 4].map(x => { return x * x });
// result is squares = [4, 9, 16]

The forEach function is more appropriate to use here since you just want to loop over the array and don't care about storing a transformation.

Then when the outer loop finishes your function can return newData

export const filterByDateTimeRange = (data=[{}], timeKey=[], startTime=moment(), stopTime=moment()) => {
  let newData = [];
  let i = 0;
  for(const item of data) {
    let time;
    let index = 0
    timeKey.forEach(key => {                         //changed to a forEach loop
      time ? time = time[key] : time = item[key];
      index++
      if(index === timeKey.length) {
        if(moment(time).isBetween(startTime, stopTime, undefined, '[)')) {
          newData.push(item)
        };
        i++;
        if(i === data.length) {
          console.log(newData);
        }
      }
    });
  }
  return newData; //add the return after your loop finishes
}

Upvotes: 2

Văn Hồng Xuân
Văn Hồng Xuân

Reputation: 1

This return inside a map function. Not return of filterByDateTimeRange(). If you want to return newData. Replace map function by for loop.

Map: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map

Upvotes: 0

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