How to call an external variable in a forEach loop in javascript

Question

I'm trying to call an external variable in a forEach context. Since I'm using an arrow notation this should make the trick but the variable still comes out as undefined.

This is my code:

transformSlots (slots) {
 var array = slots;
 var newArray;
 array.forEach(element => {
   var newElement = {
     day: dateFns.getDate(element.slot),
     month: dateFns.getMonth(element.slot),
     year: dateFns.getYear(element.slot),
     hour: dateFns.getHours(element.slot),
     numInterview: element.num,
     id_users_pending: 0,
     id_users_accepted: 0
   };
   this.newArray.push(newElement);
 });
 return array;
}

EDIT: If I take .this away the result is exactly the same.

change this.newArray.push(newElement); to newArray.push(newElement); — Krzysztof Krzeszewski
– Krzysztof Krzeszewski, Commented Feb 15, 2019 at 6:56
newArray is only declared but not assigned any value like empty array. so. doing newArray.push(newElement); will also be wrong. instarting it should be var newArray = [] then, newArray.push(newElement); — Gaurav Saraswat
– Gaurav Saraswat, Commented Feb 15, 2019 at 10:17

ellipsis · Accepted Answer · 2019-02-15 06:58:20Z

1

Remove the this. It will make the code look for newarray in the callback and not outside the loop

transformSlots (slots) {
 var array = slots;
 var newArray;
 array.forEach(element => {
   var newElement = {
     day: dateFns.getDate(element.slot),
     month: dateFns.getMonth(element.slot),
     year: dateFns.getYear(element.slot),
     hour: dateFns.getHours(element.slot),
     numInterview: element.num,
     id_users_pending: 0,
     id_users_accepted: 0
   };
   newArray.push(newElement);
 });
 return array;
}

answered Feb 15, 2019 at 6:58

ellipsis

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Comments

Carlo · Accepted Answer · 2019-02-15 08:04:45Z

0

You should use newArray.push(newElement); instead of this.newArray.push(newElement);.

If you print this in the forEach loop you'll find that the newArray isn't bind to this.

edited Feb 15, 2019 at 8:04

Carlo

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answered Feb 15, 2019 at 7:53

Larixs

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